Caterpillarwork toolquick coupler

Caterpillar PIN GRAB

Maintenance schedule, common problems & OEM parts breakdown

The Cat Pin Grabber is a hydraulic pin-grabber-style quick coupler for excavators, not a machine in its own right — it carries no engine, powertrain, or undercarriage of its own. It bolts and pins between the excavator stick/link and the work tool, letting the operator hydraulically grab and release buckets and other pin-on attachments from the cab. Cat builds the current line in a run of linkage-family sizes — 312, 315, B, CB, DB, TB, VB/VB2, and HB/HB2 — scaled to match tracked excavators from roughly the 311 through 395 class plus M313-M322 wheeled excavators, with coupler weight climbing from around 185-190 kg for the smallest B/312/315 linkages up past 1,200-1,550 kg for the largest VB2/HB2 sizes used on the biggest excavators. Current-generation couplers (factory spec sheet GEJQ9387-00, issued 2020) use a spring-loaded secondary latch that stays closed even if hydraulic pressure is lost; Cat also offers a mechanical (non-hydraulic) coupling option on some sizes alongside the standard hydraulic-actuated version.

The pin-grabber line has gone through at least one full design change: an earlier Center-Lock generation, introduced around 2009-2010 for the 311-390 range, used an over-center rocker-lock mechanism where the closing cylinder forced a rocker, connector link, and secondary lock into an over-center position to secure the tool, eliminating the blocking bar and spring pack used on still-older pin-grabber designs. The current generation replaced that over-center rocker with the simpler spring-loaded secondary-latch arrangement sold today. Because these couplers work every cycle the machine digs, the pin bores, hooks, wear plates, and lock cylinder are the parts that wear out fastest and drive the bulk of aftermarket and used-parts demand; the secondary latch and its pivot hardware are safety-critical, so rebuild kits, hooks, pins/bushings, and cylinder seal kits are the parts most commonly sourced for coupler upkeep in the used and parts market today.

Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.

Caterpillar PIN GRAB specifications

Engine

Engine	Not applicable. Pin Grabber is a passive hydraulic work tool with no engine, no ECM, and no independent power source. It is pinned onto the excavator stick/link in place of a bucket and is powered entirely by the host excavator's own hydraulic system through a dedicated hydraulic kit.
Emissions tier	Not applicable — no engine fitted.

Weights

312 Linkage weight (311-315F class)	185-188 kg (408-414 lb), excludes pins
315 Linkage weight (315D-319D class)	297-299 kg (655-659 lb), excludes pins
B Linkage weight (320-323 class)	374-380 kg (825-838 lb), excludes pins
CB Linkage weight, incl. trenching version (324-335F reach-linkage class)	430-465 kg (948-1,025 lb), excludes pins
DB Linkage weight, incl. narrow-profile version (330-340 class)	612-624 kg (1,349-1,376 lb), excludes pins
TB Linkage weight, incl. trenching version (345-352/395 class)	931-944 kg (2,053-2,082 lb), excludes pins
VB2 Linkage weight (374 class)	1,244 kg (2,743 lb), excludes pins
HB2 Linkage weight (390/395 class)	1,556 kg (3,430 lb), excludes pins
Recommended carrier (excavator) operating weight range, by linkage	312: 11-15 t; 315: 15-18 t; B: 19-23 t; CB: 24-35 t; DB: 30-40 t; TB: 45-52 t; VB2: 74 t; HB2: 90-95 t
Lift-eye working load limit, by linkage	312/315/B: 10,000 kg (22,046 lb); CB/DB: 14,000 kg (30,865 lb); TB/VB2: 20,000 kg (44,092 lb); HB2: 24,000 kg (52,911 lb)
Center-Lock generation weight variance (note)	An earlier Center-Lock version of the coupler (over-center locking design, same linkage names) publishes its own weight figures that run slightly heavier per size — e.g. 224 kg (494 lb) for 312, up to 1,842 kg (4,061 lb) for HB2/HB — do not merge these with the standard-line weights above; they belong to a separate generation.

Dimensions

Width A (at machine/carrier interface), by linkage	312: 381 mm (15.00 in); 315: 460 mm (18.11 in); B: 512 mm (20.16 in); CB: 491-550 mm (19.33-21.65 in); DB: 590 mm (23.23 in); TB: 654.5-665 mm (25.77-26.18 in); VB2: 783 mm (30.83 in); HB2: 896 mm (35.28 in)
Width B (at attachment/work-tool interface), by linkage	312: 211 mm (8.31 in); 315: 271 mm (10.67 in); B: 302 mm (11.89 in); CB: 340 mm (13.39 in); DB: 340-380 mm (13.39-14.96 in); TB: 433 mm (17.05 in); VB2: 493 mm (19.41 in); HB2: 542 mm (21.34 in)
Pin diameters, stick-front / link-rear (mixed combinations available per linkage)	312: 60-65 mm (2.36-2.56 in); 315: 70 mm (2.76 in); B: 80 mm (3.15 in); CB: 80-90 mm (3.15-3.54 in); DB: 90-100 mm (3.54-3.94 in); TB: 100-110 mm (3.94-4.33 in); VB2: 100-120 mm (3.94-4.72 in); HB2: 110-130 mm (4.33-5.12 in)
Pin spread range, by linkage (varies with pin-diameter combination selected)	312: 348-431 mm (13.70-16.97 in); 315: 399-470 mm (15.71-18.50 in); B: 443-490 mm (17.44-19.29 in); CB: 458-536 mm (18.03-21.10 in); DB: 479-593 mm (18.86-23.35 in); TB: 529-633 mm (20.83-24.92 in); VB2: 595-655 mm (23.43-25.79 in); HB2: 590-696 mm (23.23-27.40 in)
Sideplate clearance, maximum, by linkage	312: 113 mm (4.45 in); 315: 126 mm (4.96 in); B: 132 mm (5.20 in); CB/DB: 159 mm (6.26 in); TB: 169 mm (6.65 in); VB2: 180 mm (7.09 in); HB2: 190 mm (7.48 in)
Face spread range (attachment mounting-ear width compatibility), by linkage	312: 213-241 mm (8.39-9.49 in); 315: 273-297 mm (10.75-11.69 in); B: 304-327 mm (11.97-12.87 in); CB: 342-371 mm (13.46-14.61 in); DB: 342-407 mm (13.46-16.02 in); TB: 435-456 mm (17.13-17.95 in); VB2: 495-530 mm (19.49-20.87 in); HB2: 544-579 mm (21.42-22.80 in)
Machine/carrier class coverage	Full lineup spans 311-395 class hydraulic excavators plus M313-M322 wheeled excavators. Trenching versions of CB/DB/TB keep a narrower profile at the carrier interface for tight-trench digging; DB narrow-profile is the minimum acceptable size for trenching in that class. Fitting a coupler to an M-series wheeled excavator reduces work-tool rotation by about 15 degrees.

Performance

Travel speed	Not applicable — passive attachment, no travel function of its own.
Drawbar pull / gradeability	Not applicable — not a self-propelled or towed machine.
Tool-change cycle	Designed to swap buckets and other pinned work tools in seconds from the cab, versus minutes for a bolt-on/pin-on change without a coupler.
Lock mechanism	Standard line uses a primary wedge/hook plus a hinged secondary latch held by twin spring-loaded arms and a cylinder check valve, so the tool stays locked even on loss of hydraulic pressure. A separate, newer Center-Lock line replaces this with a patented over-center rocker lock plus a counterbalance valve and thicker-wall cylinder; either coupler hook alone is rated to hold the full weight of the tool if a pin is missed on engagement.
Breakout force effect	Short coupler profile is sized to preserve breakout force and digging power versus a bare bucket. When the Center-Lock coupler is paired with the matching recessed-pin performance bucket, the combination is rated for up to about 10% more breakout force than a conventional pin-on bucket-and-coupler setup — this figure is specific to that pairing, not the coupler alone.
Maintenance interval	One primary grease point (or one per hook on Center-Lock), intended for daily greasing.

Service capacities (summary)

Hydraulic system	No onboard reservoir or pump. Coupler cylinder is actuated by the host excavator's hydraulic system via a dedicated coupler hydraulic kit (lines routed through the coupler body); operating pressure/flow are set by the carrier machine and are not separately published for the attachment.
Fuel tank	Not applicable — no engine.
Engine oil	Not applicable — no engine.
Cooling system	Not applicable — no engine.

Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.

PIN GRAB fluids & capacities

System	Capacity	Recommended fluid
Engine crankcase (with filter)	Not applicable — the Pin Grabber coupler is a passive hydraulic work tool with no engine of its own.	Not applicable
Cooling system	Not applicable — no engine, no cooling system on this attachment.	Not applicable
Fuel tank	Not applicable — no engine, no fuel tank on this attachment.	Not applicable
Transmission/powertrain compartments	Not applicable — the coupler has no powertrain or drivetrain.	Not applicable
Final drives	Not applicable — the coupler has no final drives.	Not applicable
Hydraulic system and tank	No dedicated reservoir. The coupler's lock cylinder runs off the host excavator's own hydraulic circuit and pilot pressure, drawing from the carrier machine's hydraulic tank rather than carrying its own oil supply.	Use the fluid already specified for the host excavator's hydraulic system (Cat HYDO Advanced or equivalent, per the carrier machine's own OMM). No separate hydraulic fluid or capacity applies to the coupler itself.
Axles/differentials	Not applicable — the coupler has no axles or differentials.	Not applicable
Grease points (pin/hook mechanism)	Spec only, no volume figure published. One central greasing block serves the whole coupler mechanism (hook/pin joint area), accessed at ground level; apply grease until it purges from the joint. Daily greasing interval under normal duty; more frequent in severe or high-cycle applications, per dealer guidance.	Cat Prime Application Grease (NLGI Grade 2, lithium complex base with molybdenum disulfide EP additive) is the standard recommendation; effective across roughly -20°C to +140°C (-4°F to +284°F). For severe applications (heavy shock loading, extreme temperature, high-cycle attachment changes), consult your Cat dealer for an alternate grease better suited to the duty cycle.

Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.

Caterpillar PIN GRAB maintenance schedule

Service interval	Tasks
Every 10 h	Wipe pin bores, hook faces, and secondary latch clean of mud, spoil, and packed debris before greasing. Grease the pivot and pin-grab points at the coupler's grease block until fresh grease purges at each fitting. Cycle the coupler open and closed once with no attachment to confirm the lock lever and secondary latch move freely. Visually check that the shield/guard over the locking mechanism is intact and not bent into the latch path.
Every 50 h	Inspect the front and rear pin bores and hooks for elongation, scoring, or flat-spot wear against a go/no-go gauge or OEM wear limit. Confirm the secondary (safety) latch fully engages and holds without operator assist before each shift resumes work. Check the coupler-to-work-tool contact/wear plates for gouging and shim wear. Inspect visible hydraulic hose runs to the lock cylinder for chafing, leaks, or loose routing clips. Function-test the manual/hydraulic unlock sequence with an attachment mounted, confirming positive lock indication (visual or in-cab).
Every 250 h	Inspect the lock cylinder rod and barrel for seal weep, scoring, or pitting. Check hydraulic quick-disconnect fittings and hoses feeding the coupler circuit for wear, leaks, or abrasion. Verify the lock-cylinder solenoid valve and any position sensor operate and seat correctly through a full lock/unlock cycle. Re-torque accessible coupler-to-stick and coupler-to-link mounting bolts to spec. Grease all secondary pivot points beyond the daily block fitting, including hook pivot pins.
Every 500 h	Torque-check all stick, link, and bucket-pin retaining hardware and replace any deformed retainers. Measure hook and pin bore wear against OEM limits and record trend for planning replacement. Inspect wear plates and side guides for thickness loss; rotate or replace as needed. Pressure-test or function-verify the lock cylinder holds position under load with no drift. Inspect the coupler frame castings for cracking around the pin pockets and lock cylinder mounts.
Every 1,000 h	Remove and inspect the lock cylinder; reseal or rebuild if rod seals show wear or the cylinder drifts under load. Disassemble and inspect hooks, secondary latch components, and pivot pins/bushings for wear beyond service limits. Replace worn pins, bushings, and wear plates as a set rather than piecemeal to keep hook engagement square. Inspect the coupler casting and lock linkage for stress cracking, especially at the pin-grab throat and latch mounting bosses. Verify all coupler safety decals, lock-position indicators, and shields are present and legible.
Every 2,000 h	Full teardown of the coupler: strip hooks, secondary latch, lock cylinder, and all pivot hardware for a complete wear survey. Replace the full pin-and-bushing set at the coupler-to-stick and coupler-to-link joints regardless of visual condition if approaching hours-in-service limits. Rebuild or replace the lock cylinder as a unit if seal or bore wear is found during teardown. Re-machine or replace hook and pin-bore surfaces that are outside factory wear tolerance. Repaint and re-decal the coupler frame after teardown to protect against corrosion and restore safety markings.

Servicing the PIN GRAB beyond the schedule

Predictive Maintenance & Fluid Analysis

There's no engine oil to sample on a pin-grabber coupler — the useful predictive data comes from grease condition and wear trending instead. Pull grease samples from the pin-grab and hook pivot points periodically to check for metal fines that flag advancing pin/bushing wear before it becomes play in the joint. Track hook and pin-bore wear measurements at each 250-500 hour check and log the trend line so hook or pin replacement can be scheduled before the secondary latch loses reliable engagement.

Corrective & Common Repairs

The most common pin-grabber repairs are hook and pin-bore resurfacing or outright replacement once wear exceeds factory limits, since worn hooks let the work tool rock or fail to seat square. Lock-cylinder reseal is the next most frequent job when rod seals weep or the cylinder loses holding pressure under load. On couplers with a lock-position sensor or solenoid valve, intermittent lock-confirmation faults usually trace to a fouled sensor, damaged wiring, or a sticking solenoid rather than the mechanical latch itself.

Overhaul & Rebuild Points

A full coupler rebuild replaces the pin and bushing set at both the stick and link connections together, since mixing new and worn pins in the same joint reintroduces play immediately. Hooks and wear plates get rebuilt or replaced as a matched set to keep the pin-grab throat square and the secondary latch engaging correctly. The lock cylinder is rebuilt or swapped as a unit — reseal if the bore is still within tolerance, replace if scored or out of round — and the coupler casting gets inspected for cracking around the pin pockets and latch mounts before returning it to service.

Seasonal & Environment Servicing

In cold weather, switch to a low-temperature grease at the pin-grab points so the pivots and secondary latch keep moving freely instead of stiffening up in sub-zero starts. In muddy, wet, or demolition environments, clear packed debris from the pin bores and around the latch mechanism before every lock/unlock cycle, since packed mud is the most common cause of a latch that won't fully seat. Coat exposed pins, hooks, and cylinder rod surfaces to protect against corrosion during extended outdoor storage or wash-down-heavy duty cycles.

PIN GRAB fault codes & troubleshooting

Code	Meaning	Likely cause	What to do
Coupler lock indicator - solid/steady (in-cab)	Both pins are fully engaged and the secondary latch has closed over the front pin; system reads as locked.	Normal locked state, not a fault.	No action needed; visually confirm latch position before curling the attachment.
Coupler lock indicator - flashing or fails to go solid	Coupler control circuit cannot confirm the secondary latch/wedge has reached the locked position.	Low pilot/system hydraulic pressure to the solenoid block, worn or sticking latch linkage, debris in the jaw, or a wiring fault at the cab toggle switch or solenoid coil.	Cycle the lock/unlock switch with the attachment resting on the ground, inspect the latch and pins for damage or debris, then check solenoid coil continuity and switch wiring before assuming a hydraulic problem.
Continuous audible alarm in cab during coupler operation	Sequential lock/unlock control circuit is warning that the unlock step was initiated but lock confirmation was not received.	Position/proximity sensor on coupler-safety-equipped couplers not detecting the wedge in the closed position, or a failed solenoid valve stuck in the unlocked position.	Stop attachment work immediately, re-engage the pins, and run the lock sequence again; if the alarm persists, have the solenoid valve and sensor circuit checked before returning to service.
Coupler solenoid coil open/short circuit (host machine implement ECM)	On couplers wired into the excavator's own electrical/hydraulic control system, the host machine's monitor can flag a generic open-circuit or short-circuit condition on the coupler lock/unlock solenoid output.	Chafed or corroded wiring at the stick-mounted solenoid block, a failed coil, or a blown fuse/relay feeding the coupler circuit.	Check the fuse and relay for the attachment/coupler circuit first, then test the solenoid coil resistance and wiring harness for continuity and chafe points along the boom and stick.

Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.

PIN GRAB attachments & work tools

General-purpose digging buckets

Standard trenching and excavation buckets sized to the coupler's linkage family, for general dirt, clay, and mixed soil work. Capacity and width scale with the excavator size class the coupler is fitted to, from small mini-excavator ranges up through large 300-series machines.

Severe-duty / rock buckets

Reinforced buckets with heavier wear packages and bolt-on or cast cutting edges for high-abrasion, rock, and heavy digging duty. Same pin spacing as the standard bucket for a given linkage family so they swap on the same coupler without adapters.

Ditching and grading buckets

Wide, shallow-profile buckets for ditch cleaning, sloping, and finish grading. Reduced digging depth but wider cutting width than a digging bucket of the same linkage class, aimed at finishing work rather than production digging.

Thumbs (mechanical and hydraulic)

Bucket thumbs mount on the same stick/coupler pin as the bucket, either as a fixed mechanical clamp or a hydraulically actuated arm run off an auxiliary circuit. Used for handling brush, rock, pipe, and demolition debris; removable when not needed to keep the bucket at full capacity.

Compaction wheels

Passive, non-hydraulic drum-style attachments for compacting trench backfill and footings, fully compatible with the pin grabber coupler with no extra hydraulic kit needed. Sized to the carrier class, using machine hydraulic pressure/weight to roll the trench rather than vibration.

Vibratory plate compactors

Hydraulically driven plate compactors for trench and footing compaction, available with mounting brackets for pin-grabber, pin-lock, pin-on, and other coupler styles. Sized to smaller excavator classes (roughly 2.5-6 metric ton mini excavators for the smallest models); larger plate compactors extend to bigger carriers. Require a dedicated hydraulic circuit, with hoses routed inside the compactor frame.

Coupler linkage / mounting families

The pin grabber coupler is offered in multiple linkage-family sizes (B, CB, DB, TB, VB, HB, and model-specific families such as the 315-linkage) matched to the excavator's stick pin diameter and pin spacing. Adding the VB and HB sizes extended coverage across the excavator range from roughly the 311 class up through the 390 class; smaller mini-excavator classes (3-4 ton and 5 ton) use a related "dual lock" pin-grabber/pin-lock hybrid coupler.

Actuation type: hydraulic vs mechanical

Couplers are offered as hydraulic (cab-controlled via a dash switch, opened/closed on pilot pressure) or mechanical (manually actuated, no hydraulic kit needed on the machine). Hydraulic versions need a coupler hydraulic kit installed on the machine but not a full auxiliary work-tool circuit like a breaker or compactor would require.

Locking mechanism and guarding

A hydraulic cylinder drives hook-style jaws that grip the work tool's front and rear mounting pins, holding the tool against the stick and linkage. The system uses a redundant (dual) locking arrangement plus cab visual and audible confirmation that the tool is fully engaged, so it meets or exceeds international quick-coupler safety standards.

All PIN GRAB assemblies by section

Every catalogued assembly group for the Caterpillar PIN GRAB. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Hydraulic System

273-4147 Cylinder Gp-Coupler

09***28	Fitting-Grease	2
10***40	Seal-O-Ring; (12.1-mm Id)	1
17***06	Valve Group-Check; (Hydraulic Cylinder, Quick Coupler)	1
25***07	Kit-Seal; (Coupler Cylinder)	1

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256-9795 Cylinder Gp-Coupler

09***28	Fitting-Grease	2
10***40	Seal-O-Ring; (12.1-mm Id)	1
17***06	Valve Group-Check; (Hydraulic Cylinder, Quick Coupler)	1
25***07	Kit-Seal; (Coupler Cylinder)	1

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172-8402 Cylinder Gp-Coupler

09***28	Fitting-Grease	2
10***40	Seal-O-Ring; (12.1-mm Id)	1
17***02	Cylinder Group-Coupler	1
17***06	Valve Group-Check; (Hydraulic Cylinder, Quick Coupler)	1

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256-9777 Cylinder Gp-Coupler

09***28	Fitting-Grease	2
10***40	Seal-O-Ring; (12.1-mm Id)	1
17***06	Valve Group-Check; (Hydraulic Cylinder, Quick Coupler)	1
25***77	Cylinder Group-Coupler	1

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327-0338 Cylinder Gp-Hydraulic

03***57	Tee-Flared	1
08***70	Sleeve	1
10***50	Loom; (29-cm)	0
12***50	Valve-Check; (Quick Coupler Solenoid)	1

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274-6678 Cylinder Gp-Hydraulic

12***11	Coupling-Permanent	1
12***13	Coupling-Permanent	1
15***65	Hose As	1
16***10	Hose As	1

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274-5997 Cylinder Gp-Hydraulic

09***28	Fitting-Grease	2
10***40	Seal-O-Ring; (12.1-mm Id)	1
17***06	Valve Group-Check; (Hydraulic Cylinder, Quick Coupler)	1
27***97	Cylinder Group-Hydraulic	1

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169-9513 Lines Gp-Coupler

15***70	Nut; (1/2-20-2b-Thd)	1
16***13	Lines Group-Coupler	1
24***85	Valve Group-Solenoid; (Solenoid)	1
24***91	Coil As	1

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177-1401 Lines Gp-Coupler -Quick Coupler

15***46	Valve Group-Solenoid; -Quick Coupler	1
16***40	Plate-Bracket	1
17***01	Lines Group-Coupler; -Quick Coupler	1
3J***07	Seal Valve Assembly To; Seal- Tube Assembly To Logic Valve	4

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247-6295 Manifold Gp-Control

16***40	Plate-Bracket	1
24***95	Manifold Group-Control; -Quick Coupler	2
3J***07	Seal Valve Assembly To; Seal- Tube Assembly To Logic Valve	4
5C***61	Nut (M8x1.25 Thd); (M8x1.25 Thd)	4

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186-3624 Valve & Mtg Gp-Solenoid

10***02	Kit-Receptacle; (2-Pin)(Engine Sensor Wiring Harness)	1
10***36	Kit-Seal; (Solenoid Valve)	1
11***43	Locknut; (5/16-18-Thd)	1
17***85	Spool As-Valve	1

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170-2470 Valve & Mtg Gp-Solenoid

15***46	Valve Group-Solenoid; -Quick Coupler	1
16***40	Plate-Bracket	1
17***70	Valve & Mtg Group-Solenoid	1
3J***07	Seal Valve Assembly To; Seal- Tube Assembly To Logic Valve	4

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152-8346 Valve Gp-Solenoid

15***46

Valve Group-Solenoid; -Quick Coupler

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Work Tool Arrangement

303-5224 Coupler Ar-Quick

17***29	Shim; (1.0-mm Thk)	2
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1
26***72	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1

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276-3231 Coupler Ar-Quick

16***90	Shim; (1-mm Thk)(1mm)	2
26***66	Coupler Group-Quick	1
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1

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276-3217 Coupler Ar-Quick

16***90	Shim; (1-mm Thk)(1mm)	2
23***23	Coupler Group-Quick; -B1-Linkage	1
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1

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318-8207 Coupler Ar-Quick

16***90	Shim; (1-mm Thk)(1mm)	2
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1
26***72	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1

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318-8208 Coupler Ar-Quick

16***91	Shim; (1-mm Thk)(1mm)	2
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1
26***72	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1

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276-3219 Coupler Ar-Quick

17***90	Shim; (1-mm Thk)	2
23***53	Coupler Group-Quick; -Hydraulic	1
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1

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307-2942 Coupler Ar-Quick

16***91	Shim; (1-mm Thk)(1mm)	2
17***46	Pin Group-Coupler	1
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1

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268-4491 Coupler Ar-Quick -Cb-Linkage

16***91	Shim; (1-mm Thk)(1mm)	2
26***13	Coupler Group-Quick	1
26***91	Coupler Ar-Quick; -Cb-Linkage	1
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1

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268-5591 Coupler Ar-Quick

17***29	Shim; (1.0-mm Thk)	2
26***14	Coupler Group-Quick	1
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1

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276-3230 Coupler Ar-Quick

16***90	Shim; (1-mm Thk)(1mm)	2
26***65	Coupler Group-Quick	1
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1

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276-3232 Coupler Ar-Quick

16***91	Shim; (1-mm Thk)(1mm)	2
26***67	Coupler Group-Quick	1
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1

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276-3220 Coupler Ar-Quick

17***91	Shim; (1-mm Thk)(1mm Thk)	2
23***54	Coupler Group-Quick	1
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1

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307-2941 Coupler Ar-Quick

16***90	Shim; (1-mm Thk)(1mm)	2
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1
26***72	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1

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276-3218 Coupler Ar-Quick

17***89	Shim; (1-mm Thk)(1mm Thk)	2
23***52	Coupler Group-Quick	1
26***30	Film-Warning; (Crush Hazard, Read Omm, U.S.)	1
26***31	Film-Instruction; (Coupler Operation)	1

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Work Tools

265-7514 Coupler Gp-Quick

09***28	Fitting-Grease	4
11***40	Screw; (M5x0.8x19-mm)	2
26***14	Coupler Group-Quick	1
27***59	Plate-Retaining	1

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303-5968 Coupler Gp-Quick

30***68	Coupler Group-Quick	1
7Y***57	Pin; (Dia 79.85mm)	2
7Y***27	Bolt; (M16x2x190-mm)	2
8T***32	Nut (M16 X 2 Thd); (M16x2.00 Thd)	4

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297-6983 Coupler Gp-Quick

17***56	Bearing	1
27***59	Plate-Retaining	1
27***92	Pin	1
27***93	Pin	1

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297-6984 Coupler Gp-Quick

27***59	Plate-Retaining	1
27***92	Pin	1
27***93	Pin	1
27***94	Pin	1

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235-0723 Coupler Gp-Quick

09***28	Fitting-Grease	4
11***40	Screw; (M5x0.8x19-mm)	2
17***56	Bearing	1
17***02	Cylinder Group-Coupler	1

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260-1966 Coupler Gp-Quick

09***28	Fitting-Grease	4
11***40	Screw; (M5x0.8x19-mm)	2
17***56	Bearing	1
26***66	Coupler Group-Quick	1

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265-7513 Coupler Gp-Quick

09***28	Fitting-Grease	4
11***40	Screw; (M5x0.8x19-mm)	3
17***56	Bearing	1
26***13	Coupler Group-Quick	1

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236-4152 Coupler Gp-Quick

09***28	Fitting-Grease	4
11***40	Screw; (M5x0.8x19-mm)	2
18***94	Bearing	1
20***62	Spring	1

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260-1967 Coupler Gp-Quick

09***28	Fitting-Grease	4
11***40	Screw; (M5x0.8x19-mm)	2
26***67	Coupler Group-Quick	1
27***59	Plate-Retaining	1

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236-4153 Coupler Gp-Quick

09***28	Fitting-Grease	4
11***40	Screw; (M5x0.8x19-mm)	2
18***95	Bearing	1
20***63	Spring	1

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260-1965 Coupler Gp-Quick

09***28	Fitting-Grease	4
17***56	Bearing	1
17***02	Cylinder Group-Coupler	1
20***65	Spring	1

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236-4154 Coupler Gp-Quick

09***28	Fitting-Grease	4
11***40	Screw; (M5x0.8x19-mm)	2
18***96	Bearing	1
20***64	Spring	1

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268-4450 Pin Gp-Coupler

09***28	Fitting-Grease	2
10***40	Seal-O-Ring; (12.1-mm Id)	1
17***06	Valve Group-Check; (Hydraulic Cylinder, Quick Coupler)	1
17***87	Kit-Seal; (Hydraulic Cylinder, Quick Coupler)	1

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172-8473 Pin Gp-Coupler

09***49	Washer; (22x60x6-mm Thk)	1
17***73	Pin Group-Coupler	1
20***71	Washer; (26x90x8-mm Thk)	1
25***52	Pin As	1

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268-5606 Pin Gp-Coupler -Db-Linkage

09***28	Fitting-Grease	2
10***40	Seal-O-Ring; (12.1-mm Id)	1
17***06	Valve Group-Check; (Hydraulic Cylinder, Quick Coupler)	1
17***88	Kit-Seal; (Coupler Cylinder)	1

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172-8444 Pin Gp-Coupler

17***44	Pin Group-Coupler	1
20***02	Sleeve	2
28***35	Shim; (6.35-mm Thk)	2
29***69	Shim; (21-mm Thk)	2

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172-8445 Pin Gp-Coupler

10***34	Pin	2
17***45	Pin Group-Coupler	1
28***45	Shim; (1-mm Thk)	2
6V***88	Nut-Full (1/2-13 Thd); (1/2-13-Thd)(Full)	4

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172-8446 Pin Gp-Coupler

08***23	Pin Bkt To Stk Link To Bkt.	2
17***46	Pin Group-Coupler	1
6V***88	Nut-Full (1/2-13 Thd); (1/2-13-Thd)(Full)	4
7X***37	Bolt-Valve Group To Support As.	2

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172-8472 Pin Gp-Coupler

09***49	Washer; (22x60x6-mm Thk)	2
17***72	Pin Group-Coupler	1
23***31	Pin As	2
8T***23	Washer-Plated; (22x35x3.5-mm Thk)	2

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172-8471 Pin Gp-Coupler

10***78	Pin	2
17***71	Pin Group-Coupler	1
1D***99	Bolt Plate To Head	2
7X***48	Nut-Full (5/8 X 11 Thd)	4

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PIN GRAB serial number reference

The Pin Grabber PIN plate is fixed to the coupler frame itself, not the excavator's own machine PIN plate - look on the top or side of the coupler body near the hydraulic cylinder mount. The plate reads as a 3-character alphanumeric prefix (letters plus a number, e.g. PGB, XXC, BAF) followed by a running sequence number and "-UP". The prefix identifies the specific coupler-arrangement build, which in turn ties to one excavator model (or model family) and one linkage code (S, B, C, D, F, HB, DB, etc.) rather than to a model year on its own.

Prefix	Identifies	Notes
ANA1-UP	Base Quick Coupler (Hydraulic Pin Grabber) arrangement	Generic early coupler-arrangement code covering the Pin Grabber quick-coupler manual family as a whole. No single host excavator ties to this prefix specifically. Confirm exact host with dealer.
XXA1-UP	AR-Quick coupler / hydraulic-kit arrangement for the 311B-330C class excavator range	Shares a base coupler/hydraulic-kit arrangement across the 311B, 312B/C, 313B CR, 315B/C, 317, 318B, 320B/C, 321C CR, 322B, 325B, 330B/C range rather than tying to one specific model. This is not a 307-series prefix - that host belongs to XXB1.
XXB1-UP	AR-Quick coupler for 307B/C or E70B excavator, standard stick	Catalog listing ties this prefix directly to the 307B/307C/E70B excavator family with standard stick.
XXC1-UP	AR-Quick coupler for 311B or 312B/C excavator, standard stick	Catalog listings place this prefix on the 311B/312B/C family with standard stick; also appears grouped with a wider 311B-330B coupler-lines kit.
XXD1-UP	Coupler arrangement for 315B excavator	Catalog listing ties this prefix specifically to the 315B.
PGA1-UP	AR-Quick coupler, CB-linkage	Catalog listing identifies this as the CB-linkage AR-Quick coupler arrangement. No specific host excavator model number surfaced, only the linkage family.
PGB1-UP	AR-Quick coupler for 322C excavator, S-linkage	One listing ties it to the 322C with S-linkage; a second reference broadens it to S-or-B linkage machines. Treat linkage detail as approximate.
PGC1-UP	AR-Quick coupler, C-linkage	Catalog listing identifies this as the C-linkage AR-Quick coupler arrangement, same family as PGB/PGD. No specific host model number given beyond the linkage family.
PGD1-UP	AR-Quick coupler, D-linkage	Catalog listing identifies this as the D-linkage AR-Quick coupler arrangement in the same family as PGA/PGB/PGC. No specific host model number given beyond the linkage family.
PGK1-UP	Coupler group for 330D excavator, DB-linkage	Parts-manual page (Type 2 AR-Quick coupler) explicitly names the 330D with DB-linkage as the host.
PGF1-UP	Pin Grabber coupler arrangement, host not confirmed	Only turns up on a repair-kit listing without a stated host excavator or linkage. Single source only - confirm exact host machine and linkage with a Cat dealer before relying on it.
BAF1-UP	Coupler for 345B/345C/350 excavator, F-linkage	Parts-manual references tie this prefix to the 345B, 345C, and 350 excavators with F linkage (one reference lists an F-or-T linkage variant). Broader host range than a single 345B, a larger excavator class than the 3-2-series couplers above.
BTP1-UP	Coupler group for 365B excavator, shared with 345B/350	Catalog listing places this prefix on the 365B excavator with U, B, or V linkage, shared with 345B and 350 in the same arrangement - the largest host class identified for this coupler family.
PBX1-UP	Coupler for 385/385B excavator, HB-linkage	Catalog listings tie this prefix to the 385 and 385B excavator with HB linkage.
GWA1-UP	Center Lock Pin Grabber coupler, DB-linkage	Separate Center Lock sub-line of the Pin Grabber coupler family (distinct parts-manual set from the standard AR-Quick/GP-Quick line above), covering excavators from the 311 through 385 class. Catalog listings also show it split into B-linkage and CB-linkage arrangements under the same base prefix.
ANH1-UP	Pin Grabber coupler arrangement, host not confirmed	Listed alongside ANA1/ADD1/APK1 in the 2003-revision Pin Grabber parts manual, but no host excavator or linkage detail surfaced independently. Single source - confirm with dealer.
ADD1-UP	Pin Grabber coupler arrangement, host not confirmed	Same 2003-revision parts manual grouping as ANH1/APK1; no independently confirmed host machine. Confirm with dealer.
APK1-UP	Pin Grabber coupler arrangement, host not confirmed	Same 2003-revision parts manual grouping; no independently confirmed host machine. Confirm with dealer.
BAT1-UP	Pin Grabber coupler arrangement, host not confirmed	Appears in the same manual family as BAF1/BBA1/BBZ1. Repeat lookups gave conflicting host-machine attributions for this prefix, so no single host is reliable enough to publish. Confirm with dealer.
BBA1-UP	Pin Grabber coupler arrangement, host not confirmed	Same manual grouping as BAT1/BBZ1; no independently confirmed host machine survived cross-check. Confirm with dealer.
BBZ1-UP	Pin Grabber coupler arrangement, host not confirmed	Same manual grouping as BAT1/BBA1; no independently confirmed host machine survived cross-check. Confirm with dealer.
B9A1-UP	Pin Grabber coupler arrangement, host not confirmed	Listed in the same 2003 parts-manual family; only turns up as part of a coupler group number without a stated host excavator. Confirm with dealer.

Frequently asked questions

Does the Pin Grabber coupler have its own engine?

No. The Pin Grabber is a passive hydraulic attachment with no engine, transmission, or undercarriage of its own — it draws its hydraulic power entirely from the host excavator.

What powers the Pin Grabber coupler's lock cylinder?

The host excavator's own hydraulic system powers the coupler's lock cylinder through the machine's auxiliary or coupler circuit; the coupler has no independent power source, so lock/unlock function depends on the carrier machine's hydraulics being live.

How much does a Pin Grabber coupler weigh?

Weight varies by linkage-size class: roughly 185-190 kg for the smallest B/312/315-linkage couplers, around 300-465 kg for the mid-size CB/DB/TB linkages, and up to about 1,244-1,556 kg for the largest VB2/HB2 linkages used on the biggest excavators in the range.

What coupler design did the Pin Grabber replace?

The current spring-loaded secondary-latch Pin Grabber (spec sheet GEJQ9387-00) superseded an earlier Center-Lock generation that used an over-center rocker-lock mechanism to secure the work tool; that Center-Lock design itself had replaced still older pin-grabber couplers that relied on a blocking bar and spring pack.

What PIN GRAB owners discuss

How does the hydraulic Pin Grab coupler actually lock and unlock — what powers it?

The coupler has no pump or circuit of its own. It taps into the excavator's bucket cylinder curl circuit through an electrically controlled valve. The operator flips a cab switch, then curls the bucket to the end of stroke and holds it against relief; that diverted pressure drives the coupler's internal lock cylinder open or closed. Because the coupler rides on bucket-curl pressure, a machine with low main relief setting or a curl circuit already in poor shape can make the coupler feel slow or reluctant to open, even though the coupler itself is fine. If lock/unlock is sluggish or inconsistent, check base machine curl-circuit pressure and relief settings before condemning the coupler.

Is there a real safety risk if the secondary latch/lock isn't confirmed before lifting?

Yes, and it is the single most-discussed safety issue with pin-grab style couplers industry-wide, not specific to one brand. Documented incidents (tracked by US safety agencies since the late 1990s) trace back almost entirely to operators lifting an attachment before the secondary mechanical lock was verified engaged, relying on the primary hydraulic lock alone. The Pin Grab's secondary latch is spring-loaded and mechanically independent of hydraulic pressure specifically so the attachment stays captured if the lock cylinder loses pressure — but that only works if the latch actually swung home. Operators are trained to visually confirm the latch position (and any indicator flag/window) and do a ground-level shake test before curling up. Treat any alarm, indicator light, or visual latch position as advisory only — have your dealer verify the secondary latch and any position-sensing circuit before returning the coupler to service after any lock complaint.

What wear should I expect at the pin bores and hooks, and how much play is too much?

Wear shows up as a rocking or clunk between the attachment and coupler when the bucket is on the ground and the stick is worked, most noticeable in the curl/dump direction. Some slack is normal over time as the hook/wedge faces and pin bores wear; the coupler is not expected to run tight indefinitely. What owners flag as a problem is play severe enough to produce an audible knock under load or visible movement by eye, not just a barely perceptible looseness. Grease intervals matter — starved pin bores wear noticeably faster than a properly greased coupler. Reported wear life is highly duty-cycle dependent (rock/demolition work chews through hook faces far faster than grading or utility work), so treat any specific hour figure as a range, not a guarantee.

What causes a lock/unlock alarm that won't clear even though the attachment looks fully engaged?

Owners report this exact complaint: the coupler cycles, the attachment looks seated, but the in-cab alarm keeps sounding until the machine is shut down and restarted. Reported causes span the whole signal path — a proximity/position sensor that's misaligned, contaminated, or reading a partial engagement; a solenoid coil with a wiring or connector fault (corrosion, chafed harness); or debris/varnish inside the valve the solenoid actuates so it doesn't fully shift. Because this is a locking-confirmation signal, don't treat a persistent alarm as a nuisance to silence — have your dealer verify sensor alignment, solenoid function, and valve condition before trusting the coupler's lock state again.

What should I inspect when buying a used Pin Grab coupler?

Check the pin bores and hooks/wedges for wear by working the attachment against the ground and watching for rocking or knock in the joint — this is the main tell for hours put on the coupler. Cycle the lock/unlock function multiple times and confirm the secondary latch swings fully home and holds every time, not just most of the time. Look at the lock cylinder for external seal weeping and check that it holds position without creeping when pressure is removed. Confirm the safety/warning decals and any indicator windows are present and legible — missing placards are a common sign of a coupler that's been repainted or moved between machines without full documentation. Ask for any history of coupler-related incidents or repairs, and have your dealer verify hook/pin wear against factory limits and confirm the sensor/solenoid circuit checks out before you rely on it.

Will a Pin Grab coupler from one excavator size fit a different machine or bucket?

Not automatically. Cat builds the Pin Grab family across several distinct linkage/frame families sized to excavator weight class, and pin spacing, tip radius, and mounting geometry differ between them — a coupler and its mating buckets are only interchangeable within the same linkage family and roughly the same size class of machine. Swapping across families, or mixing a Pin Grab coupler with buckets built for a wedge-style coupler, is a common source of fitment questions; if you're pairing a used coupler with a machine or bucket it didn't come with, verify linkage family and pin geometry match before assuming it will bolt up.

How does the Pin Grab design compare to a wedge-style coupler in everyday use?

The two designs solve the pin-to-pin connection differently and that shows up in daily use. A wedge coupler self-tightens as it wears — the wedge rides deeper into the pin pocket over time, taking up slack automatically, but it locks the bucket in one orientation and can't reverse it. A Pin Grab-style coupler grips both pins directly, which lets the operator flip the bucket around (dig one way, back-drag the other) as a standard capability, but it does not have a built-in self-adjusting wear feature — once hook or bore wear opens up play, that play stays until the coupler is serviced or rebuilt rather than tightening itself out. Neither design is universally 'better'; the trade-off is bucket reversibility versus self-compensating wear, and the choice tends to follow the type of work the machine does.

Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.

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