Caterpillar GLS60
Maintenance schedule, common problems & OEM parts breakdown
The Cat GLS60 is a hydraulic grapple-shovel logging work tool, not a self-propelled machine: it carries no engine, transmission, or hydraulic power source of its own and runs entirely off the host excavator's hydraulic system. It mounts to a factory heel-boom linkage on the boom, not a stick-mounted quick coupler, using a pin group to secure the grapple head and a dedicated cylinder-and-lines group to tie its functions into the carrier's hydraulic circuit. Compatible hosts are Cat 320B, 322B/322C, 325B/325C, and 330B/330C excavators fitted with the heel-boom option. Beyond jaw open/close, the GLS60 has a separate heel function and a hydraulic rotator (gerotor motor plus rotator group) that turns the grapple head. It sits within Caterpillar's GLS55/GLS60/GLS63/GLS66 grapple-shovel lineup, a family that scales up in size through the series and is identified in Cat's parts system by the GLS60's own GRB1-UP serial-prefix block.
In the field, the GLS60 works forestry and log-handling duty at landings, decks, and mill yards: loading trucks, sorting log piles, and building or breaking down log decks where volume and cycle speed matter more than delicate placement. Its heel is what sets a shovel-logging grapple like this apart from a plain digging bucket - folding against the boom to pin the log's butt end during travel keeps the load controlled and shields the boom face and routed hydraulic hoses from swing damage between grabs. The GLS60 is no longer a current-production Caterpillar work tool, but it remains a genuine, factory-documented attachment: Caterpillar's parts system still carries it under its own serial-prefix block, so pins, bushings, cylinder seals, and rotator components stay obtainable for owners running these units well past their original service life, which keeps used GLS60 units and their parts in steady demand.
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 GLS60 specifications
Configuration / Identification
| Work tool type | Hydraulic grapple-shovel logging attachment (Cat product category: Grapple-Shovel Logging). No onboard engine, fuel tank, cooling system, or travel speed — it is powered entirely by the host excavator's hydraulic system. |
| Product family | Part of the GLS55 / GLS60 / GLS63 / GLS66 hydraulic excavator forestry grapple lineup. Model size increases through the series; the GLS60 is identified in Cat's parts system by serial prefix GRB (GRB1-and-up). |
| Mounting | Factory-matched heel-boom grapple, paired with the factory logging front on the excavator carrier rather than a standard stick-mounted bucket linkage. |
Compatible Host Machines
| Excavator carriers | Cat 320B, 322B/322C, 325B/325C, and 330B/330C hydraulic excavators fitted with the heel-boom (log loader front) option. |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
GLS60 fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Grapple pivot pins, bushings and jaw/tilt linkage | Not published; grease each fitting until fresh grease purges at the joint | Cat multipurpose EP grease, NLGI grade chosen for ambient temperature per Cat work tool lubrication guidance; no GLS60-specific grease brand name found in available documentation |
| Rotator drive/bearing | Not published | Cat multipurpose EP grease per Cat work tool lubrication guidance; no GLS60-specific brand or quantity found in available documentation |
| Hydraulic power supply | No separate reservoir on the work tool itself | The GLS60 has no engine, tank, or hydraulic reservoir of its own; it runs off the host excavator's (320B, 322B/C, 325B/C, or 330B/C with heel-boom option) auxiliary hydraulic circuit. Follow the host machine's own operation and maintenance manual for hydraulic oil type and capacity. |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar GLS60 maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 10 h |
|
| Every 50 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 2,000 h |
|
Servicing the GLS60 beyond the schedule
Predictive Maintenance & Fluid Analysis
The GLS60's rotator and jaw/heel cylinders run entirely off the host excavator's hydraulic supply, so fluid cleanliness there is the leading predictor of rotator and valve life on this attachment. Track rotation strength in both directions at each inspection; a growing gap between directions signals a sticking relief or check valve, not a failing motor. Watch jaw and heel cylinders for slow drift under a held load, the first sign of a worn holding valve. Check pin and bushing joints for early knock before it becomes bore wear.
Corrective & Common Repairs
Most GLS60 repairs are jaw, heel, and rotator wear items tied to this attachment's shock-load duty cycle. Worn pins and bushings at those joints are replaced as matched sets, never a used bushing against a new pin. A cylinder that drifts open under a suspended log gets its holding valve replaced, since a creeping jaw under load is a drop hazard. Rotation strong one way and weak the other traces to the relief or check valve before the motor is blamed. Chafed heel hoses are replaced before they fail.
Overhaul & Rebuild Points
A full GLS60 rebuild works through the jaw, heel, and rotator group together. Pins, bushings, and bearing sleeves at every joint are pulled and replaced as complete sets, and any bore found egged-out from shock loading is built up and rebored rather than fitted with an oversize pin. Jaw and heel cylinders are stripped, resleeved, and reassembled with new seals and a verified holding valve. The rotator gerotor motor is overhauled or replaced if weakness persists after valve checks. Frame and yoke welds are crack-checked before return to service.
Seasonal & Environment Servicing
Cold-weather service on the GLS60 is mostly grease: switch to a low-temperature grease at jaw, heel, and rotator pivots below the standard grease's rated range, and cycle jaw, heel, and rotate fully before loading to work grease into cold joints. In muddy, debris-heavy log-yard conditions, clear packed dirt from pin bosses and fittings daily so grease reaches the joint. Because this attachment runs on the host's hydraulic supply, keep that fluid clean; contamination degrades the rotator and valves fastest. Protect exposed pins and rods from corrosion during off-season storage.
GLS60 fault codes & troubleshooting
| Code | Meaning | Likely cause | What to do |
|---|---|---|---|
| CID 574 | Host excavator ECM code for the grapple detent solenoid circuit, the electro-hydraulic function that holds/releases the grapple jaw detent. Typically reported as FMI 03 (open circuit or short to +battery) or FMI 04 (short to ground). | Damaged, pinched, or corroded wiring/connector in the work-tool harness between the excavator boom or heel-boom mount and the grapple solenoid, or a failed solenoid coil in the grapple control valve. | Inspect and test the work-tool harness and connector at the stick/heel-boom disconnect, check solenoid coil resistance against spec, repair the wiring or replace the solenoid. |
| CID 1809 | Work tool open solenoid circuit on the host excavator, the output that drives the grapple jaw open. Commonly reported as FMI 03 (open/short-high) or FMI 04 (short-low). | Open or shorted wiring to the work-tool valve section, corroded pins at the boom-tip connector, or a seized/failed solenoid. | Check harness continuity and connector condition from the cab switch to the valve, measure solenoid coil resistance, replace the coil or repair wiring as needed. |
| CID 1810 | Work tool close solenoid circuit on the host excavator, the output that drives the grapple jaw closed. Commonly reported as FMI 03 (open/short-high) or FMI 04 (short-low). | Same failure modes as the open-side circuit: chafed harness, corroded connector, or a failed solenoid coil on the close side of the work-tool valve. | Verify power and ground at the solenoid connector, test coil resistance, repair harness or replace the solenoid. |
| CID 1180 / CID 1181 | Auxiliary hydraulic solenoid #1/#2 circuits that meter flow to the boom-tip auxiliary circuit the GLS60 relies on for grapple actuation (used with the heel-boom/auxiliary-hydraulics option). Reported as FMI 03 or FMI 04 for an electrical fault on the driver. | Wiring or connector fault on the auxiliary valve solenoid, or an auxiliary-flow calibration not set for the work tool in use. | Confirm the auxiliary hydraulics/work-tool configuration is set correctly on the monitor, inspect the aux solenoid wiring and connector, and recalibrate or replace the solenoid if the electrical fault persists. |
Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.
GLS60 attachments & work tools
Host machine compatibility
The GLS60 grapple-shovel is a work tool for Cat 320B, 322B/322C, 325B/325C, and 330B/330C hydraulic excavators fitted with the heel-boom option. It is not sold as a standalone machine; it requires one of these host carriers set up for forestry/log-handling duty.
Mounting/coupler system
The grapple mounts to the excavator's boom-mounted heel linkage rather than a stick-mounted quick coupler. A pin group secures the grapple head to the heel-boom structure, and a dedicated cylinder-and-lines group connects the grapple's clamp/rotate function to the carrier's hydraulic circuit.
Hydraulic-kit / heel-boom arrangement requirement
Running the GLS60 requires the host excavator's factory heel-boom arrangement, which centers the grapple's hydraulic hoses over the heel pivot so they are shielded from damage during loading and sorting. The grapple's own cylinder and hose group ties into this heel-boom circuit rather than a standard stick-and-bucket linkage.
Notable factory configuration
The GLS60 uses an opposed-jaw, shovel-style grapple head built for high-volume log loading, sorting, and mill-yard decking work rather than felling. It is one of four grapple-shovel models (GLS55, GLS60, GLS63, GLS66) that Caterpillar documents together as sharing the same 320B/322B-C/325B-C/330B-C heel-boom host-machine compatibility list.
All GLS60 assemblies by section
Every catalogued assembly group for the Caterpillar GLS60. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Frame And Body
249-5124 Cover Gp-Access
| 24***04 | Plate | 1 |
| 24***23 | Plate | 2 |
| 24***15 | Plate As | 2 |
249-1008 Cover Gp-Access
| 24***04 | Plate | 1 |
| 24***23 | Plate | 2 |
| 24***08 | Cover Group-Access | 1 |
Hydraulic System
249-1006 Cylinder & Lines Gp-Grapple
| 18***78 | Hose As | 4 |
| 24***97 | Cylinder Group-Hydraulic | 2 |
| 24***06 | Cylinder & Lines Group-Grapple | 1 |
249-5099 Cylinder & Lines Gp-Grapple
| 17***03 | Hose As | 4 |
| 24***99 | Cylinder & Lines Group-Grapple | 1 |
| 24***00 | Cylinder Group-Hydraulic; -Grapple | 2 |
249-0997 Cylinder Gp-Hydraulic
| 11***13 | Kit-Seal | 1 |
| 1B***67 | Bolt, Hex. Hd., 5/8"-11 N.C. X 3" | 8 |
| 24***97 | Cylinder Group-Hydraulic | 1 |
249-5100 Cylinder Gp-Hydraulic
| 11***13 | Bolt-Hex Head; (M16x2x70mm) | 6 |
| 16***84 | Kit-Seal | 1 |
| 18***92 | Valve As-Counterbalance | 1 |
261-4654 Motor Gp-Gerotor
| 26***51 | Valve As-Relief; (1500-Psi) | 1 |
| 26***52 | Valve As-Relief; (2000-Psi) | 1 |
| 26***53 | Valve As-Relief; (3000-Psi) | 1 |
249-0172 Rotator Gp-Hydraulic
| 22***82 | Gear & Bearing As | 1 |
| 22***96 | Gear-Pinion; (13-Teeth) | 1 |
| 23***11 | Kit-Seal; (Manifold) | 1 |
Service Equipment And Supplies
249-3153 Film Gp
| 15***35 | Film-Warning; (Crush Hazard, Stay Back) | 2 |
| 15***36 | Film-Warning; (Read Operation Manual) | 2 |
| 24***09 | Film; (Cat, Gls63) | 2 |
249-3151 Film Gp
| 15***35 | Film-Warning; (Crush Hazard, Stay Back) | 2 |
| 15***36 | Film-Warning; (Read Operation Manual) | 2 |
| 24***51 | Film Group | 1 |
249-3154 Film Gp
| 15***35 | Film-Warning; (Crush Hazard, Stay Back) | 2 |
| 15***36 | Film-Warning; (Read Operation Manual) | 2 |
| 24***12 | Film; (Cat, Gls66) | 2 |
249-3152 Film Gp
| 15***35 | Film-Warning; (Crush Hazard, Stay Back) | 2 |
| 15***36 | Film-Warning; (Read Operation Manual) | 2 |
| 24***08 | Film; (Cat, Gls60) | 2 |
Work Tool Arrangement
243-5482 Grapple Ar-Shovel -Gls60
| 24***82 | Grapple Ar-Shovel; -Gls60 | 1 |
| 24***43 | Grapple Ar-Shovel | 1 |
249-3146 Grapple Ar-Shovel
| 24***14 | Housing As | 1 |
| 24***27 | Tube | 4 |
| 24***94 | Crosshead As | 1 |
243-5483 Grapple Ar-Shovel -Gls63
| 24***83 | Grapple Ar-Shovel; -Gls63 | 1 |
| 24***45 | Grapple Ar-Shovel | 1 |
249-3145 Grapple Ar-Shovel
| 24***14 | Housing As | 1 |
| 24***94 | Crosshead As | 1 |
| 24***76 | Shell As | 1 |
249-3143 Grapple Ar-Shovel
| 24***14 | Housing As | 1 |
| 24***27 | Tube | 4 |
| 24***28 | Shell As | 1 |
243-5484 Grapple Ar-Shovel -Gls66
| 24***84 | Grapple Ar-Shovel; -Gls66 | 1 |
| 24***46 | Grapple Ar-Shovel | 1 |
249-3142 Grapple Ar-Shovel
| 24***94 | Crosshead As | 1 |
| 24***72 | Rotator Group-Hydraulic | 1 |
| 24***38 | Shell Group-Grapple | 1 |
243-5481 Grapple Ar-Shovel -Gls55
| 24***81 | Grapple Ar-Shovel; -Gls55 | 1 |
| 24***42 | Grapple Ar-Shovel; -Gls55 | 1 |
Work Tools
249-3155 Fastener Gp-Work Tool
| 09***73 | Bolt; (Socket Head) (M12x1.75x60mm) | 4 |
| 24***55 | Fastener Group-Work Tool | 1 |
| 2L***01 | Bolt; (5/8-18x1.5-In) | 2 |
249-5165 Fastener Gp-Work Tool
| 09***73 | Bolt; (Socket Head) (M12x1.75x60mm) | 4 |
| 24***65 | Fastener Group-Work Tool | 1 |
| 25***30 | Spacer; (16.27x25.4x10.7-mm Thk) | 2 |
249-2901 Pin Gp-Grapple
| 12***13 | Pin-Keeper | 1 |
| 24***92 | Pin As | 2 |
| 24***94 | Plate | 1 |
249-5159 Pin Gp-Grapple
| 24***92 | Pin As | 2 |
| 24***94 | Plate | 1 |
| 24***07 | Plate | 4 |
GLS60 serial number reference
The ID/serial plate for this work tool is riveted to the grapple frame itself, not a full-machine PIN plate like a self-propelled unit. The plate shows a 3-letter parts-book prefix (here GRB) followed by a sequential unit number; the prefix ties the attachment to the correct cylinder, cover, and rotator group listings in the parts catalog rather than to a plant code or model year.
| Prefix | Identifies | Notes |
|---|---|---|
| GRB1-UP | Grapple-shovel logging assembly, single parts-book production run for the GLS60 (mounts on 320B, 322B/C, 325B/C or 330B/C excavators fitted with the heel-boom option) | Written in full as GRB00001-UP in the work-tool parts catalog; open ("-UP") breakpoint, no later GLS60-specific block found. |
Frequently asked questions
What host machines does the GLS60 fit?
The GLS60 fits Cat 320B, 322B/322C, 325B/325C, and 330B/330C hydraulic excavators fitted with the heel-boom (log-loader front) option. It is not a standalone machine and is not designed as a bolt-on for a standard digging excavator; the host needs the factory heel-boom hydraulic circuit and reinforced boom/stick to supply proper flow and pressure and to handle shovel-logging shock loads.
Does the GLS60 rotate, and how does the heel work?
Yes. Rotation is powered by a hydraulic gerotor motor and rotator group that turns the grapple head, separate from jaw open/close. The heel is a separate function again: it folds down against the boom to pin the log's butt end during travel, protecting the boom face and hoses and giving the operator a second point of control on the log besides jaw closure.
What family or lineup is the GLS60 part of?
The GLS60 belongs to Caterpillar's GLS55/GLS60/GLS63/GLS66 grapple-shovel logging lineup, a family of heel-boom grapples that increases in size through the series and shares the same 320B/322B-C/325B-C/330B-C host-machine compatibility. The GLS60 itself is identified in Cat's parts catalog by its own serial-prefix block, GRB1-UP.
What GLS60 owners discuss
How does the heel actually work on a grapple-shovel like the GLS60, and why does it matter?
What pin and bushing wear pattern shows up on this type of grapple-shovel?
What hydraulic rotator and cylinder problems come up on this class of grapple?
What should someone know about host-excavator compatibility before running a GLS60?
What routine maintenance issues come up most with a heel-boom grapple-shovel like this?
What should someone check when evaluating a used GLS60?
Is there much dedicated online discussion specifically naming the GLS60?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
Need a specific GLS60 part?
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