Caterpillarwork toolcold planer

Caterpillar PC4

Maintenance schedule, common problems & OEM parts breakdown

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The Cat PC4 is a passive, non-self-powered cold-planer work-tool attachment built for skid steers, compact track loaders, and backhoe loaders. It carries no engine and no ECM of its own; a direct-drive, variable-speed gerotor hydraulic motor turns the drum off the host carrier's standard-flow hydraulic circuit, roughly 53-83 L/min at 172-227 bar. It weighs about 522 kg (1150 lb) and measures roughly 1676 x 1168 x 762 mm, dating to Cat's legacy skid-steer cold-planer line documented around 1999-2000. It's the larger of two standard-flow siblings: PC3 cuts a 305 mm (12 in) path, PC4 a 406 mm (16 in) path with a 470 mm cut diameter, while the high-flow PC6 and PC9 cut wider still and need a higher-volume circuit. The PC4 offers a standard 406 mm drum or optional narrower kits (64/102/152 mm), manual hand-crank depth adjustment with independent left/right control, a ratcheting screw-jack tilt mechanism, hydraulic side shift with 559 mm of travel and up to 19 degrees of tilt, and a four-skid pivoting chassis. It mounts to a standard Cat skid-steer quick-coupler plate with flat-face hydraulic couplers for hookup.

Within the legacy family, the main split is standard-flow (PC3/PC4) versus high-flow (PC6/PC9), not a lettered generation change within the PC4 itself; no confirmed direct successor to the PC4 is documented. Cat's current PC104-PC412 cold-planer line is a separate, later product family with its own mounting and hydraulic requirements, and shouldn't be read as a replacement for the legacy PC3/PC4 generation. In the used and parts market, the PC4 still matters because plenty of older skid steers and loaders run standard-flow circuits well suited to utility planing work like patching, curb and gutter cuts, and small pothole or overlay prep, where a full-size high-flow planer is overkill. Value and usability turn mostly on drum, bit, and gerotor-motor condition, since a worn drum or failed motor can cost more to replace than a used unit is worth. Buyers should confirm the exact serial with a dealer before ordering parts, since the PC3 and PC4 are documented together in a shared operator and parts manual.

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 PC4 specifications

Engine

Power sourceNo onboard engine. Passive skid steer/compact loader work tool, hydraulically driven entirely off the host carrier machine's standard-flow auxiliary circuit.
Drive methodGerotor-style hydraulic motor, direct drive to the cutting drum. Variable speed, uni-directional.
Emissions tierNot applicable - no engine or ECM on the work tool itself.

Weights

Operating/shipping weight522 kg (1150 lb), per the factory work-tool spec sheet. Single configuration; no weight variants published.

Dimensions

Overall width1676 mm (66 in)
Overall length1168 mm (46 in)
Overall height762 mm (30 in)
Maximum (standard) drum/working width406 mm (16 in)
Optional narrower drum widths64 mm (2.5 in), 102 mm (4 in), 152 mm (6 in) - for specialty/utility planing jobs such as line removal
Drum cut diameter470 mm (18.5 in)
Sideshift travel559 mm (22 in), manual selector valve at the main carriage
Tilt angle range±19°, adjusted via a ratcheting screw jack

Performance

Travel speedNot applicable - this is a carried work tool, not self-propelled; ground travel is governed by the host skid steer/compact loader.
Drum speed at max flow212 rpm
Cutting-bit speed at max flow313 mpm (1026 fpm)
Drum torque at max pressure1429 N·m (1051 lb-ft)
Maximum depth of cut (mechanical)127 mm (5 in)
Recommended productive cutting depthUp to 51 mm (2 in) in asphalt and 10 mm (0.38 in) in concrete for standard-flow utility planing
Bit type and countAll-purpose conical bits standard; concrete bits optional
GradeabilityNot applicable - not self-propelled

Service capacities (summary)

Required hydraulic flow range53-83 L/min (14-22 gpm), supplied by the host skid steer/compact loader's standard-flow circuit
Optimal hydraulic pressure range172-227 bar (2500-3300 psi)
Fuel, engine oil, cooling systemNone - the work tool has no engine or independent fluid systems; all hydraulic power is drawn from the carrier machine

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

PC4 fluids & capacities

SystemCapacityRecommended fluid
Grease points (universal joints, frame pivots, depth and angle adjustment linkage)no reservoir capacity — service is per-zerk grease application, not a fill volume; apply until fresh grease purges at the jointCat Multipurpose Grease (Cat MPGM); standard NLGI grade for general service, with a lower NLGI grade recommended in sub-zero climates for easier gun pumpability
Hydraulic system (cylinder and gerotor drive motor)not applicable on the attachment itself — the cold planer has no dedicated tank; it draws oil from the carrier machine's own hydraulic circuit through quick-disconnect couplersmatch whatever hydraulic oil spec the host carrier (skid steer, compact track loader, or backhoe loader) already runs — check that machine's own OMM fluid chart, not this attachment's manual
Engine, cooling system, fuel tank, transmission/powertrain, final drives, axlesnot applicable — the PC4 is a passive, non-powered work tool with no engine, cooling system, fuel tank, transmission, final drives, or axles of its ownnone required; all motive power and cooling come from the carrier machine

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

Caterpillar PC4 maintenance schedule

Service intervalTasks
Every 50 h
  • Grease all points with Cat MPGM grease: cylinder pivots, side-shift rods, depth-skid pivots, and wheel/skid bearings; wipe off excess.
  • Inspect cutting bits for chipping, flat spots, or seized (non-rotating) picks and replace any that fail to spin freely.
  • Check flat-face hydraulic couplers and hoses for leaks, cuts, or crushed fittings before hooking up to the carrier.
  • Confirm the case-drain hose is routed without kinks or pinches to protect the motor shaft seal.
  • Wipe down the drum housing and confirm all four skid shoes sit flat against the work surface.
Every 250 h
  • Rotate the drum by hand through several full turns to confirm every bit holder spins freely; free or replace seized holders.
  • Check the drum for visible runout or wobble and tighten or replace worn bearings or bushings.
  • Work the hand-crank depth screw and ratcheting tilt jack through full travel, lubricate threads, and correct any binding.
  • Inspect side-shift slide rails and wear pads for scoring or looseness; regrease and adjust.
  • Check the quick-coupler mounting plate, pins, and latches for wear against the carrier's coupler.
Every 500 h
  • Inspect the gerotor hydraulic motor housing and shaft seal for external leaks or weeping.
  • Replace any hose showing surface cracking, abrasion, or bulging.
  • Check the independent left/right depth-control linkage for slack and recalibrate depth settings.
  • Inspect and regrease the pivots and bushings on the four-skid pivoting chassis.
  • Cycle the side-shift and tilt mechanism to confirm full 559 mm travel and full tilt range without binding.
Every 1,000 h
  • Pull a sample of the carrier's hydraulic oil for fluid analysis and check for metal content indicating gerotor motor wear.
  • Remove bit holders and check base wear, not just the bits; replace worn holders.
  • Check drum shaft bearings and seals and replace if runout is outside allowable limits.
  • Re-torque all structural fasteners on the drum housing and moldboard/skirt.
  • Measure skid-plate thickness and replace any skids worn below allowable limits.
Every 2,000 h
  • Overhaul the gerotor motor shaft seal and coupling.
  • Inspect the drum shell itself for thinning from the cutting pattern and assess whether it needs replacement.
  • Rebuild the side-shift cylinder and tilt-jack assembly with new bushings and seals.
  • Replace hoses and couplers across the whole hydraulic circuit as a set if the unit has seen heavy cumulative use.
Every 4,000 h
  • Perform a full teardown inspection of the drum, bearings, motor, and depth/tilt/side-shift mechanisms.
  • Replace all wear bushings, pivot pins, and seals as a set rather than piecemeal.
  • Strip and repaint the housing and skirts to expose any hidden structural wear or cracking.
  • Reassess whether the cutting drum assembly itself is due for replacement given cumulative wear.

Servicing the PC4 beyond the schedule

Predictive Maintenance & Fluid Analysis

The PC4 has no engine oil or coolant to sample. The fluid that matters is the host carrier's hydraulic oil feeding the gerotor motor. Pull samples at the carrier's scheduled hydraulic service intervals and watch for metal content, which flags gerotor motor wear before it fails outright. If drum speed feels sluggish or bit wear looks uneven, check case-drain flow and pressure at the coupler with a flow meter, since reduced case-drain flow is usually the earliest sign of a failing motor shaft seal.

Corrective & Common Repairs

Most PC4 repairs are bit, holder, and coupler jobs, not engine work. Replace picks that are chipped, flat-spotted, or seized in the holder; a bit that won't rotate chews out its pocket and forces a holder replacement too. Reseat or replace flat-face couplers and hoses that weep at the carrier connection, a common failure point on a tool swapped between machines often. Work a bound hand-crank depth screw or ratcheting tilt jack free with penetrant and fresh grease before forcing it, since stripped threads mean a shop repair.

Overhaul & Rebuild Points

Overhaul centers on the gerotor motor, drum shaft, and adjustment hardware, since the PC4 carries no engine or final drives to rebuild. Pull the motor for shaft-seal and coupling wear once case-drain leakage or slow drum speed shows up. Check drum-shaft bearings for play and the drum shell itself for cutting-pattern thinning. Rebuild the side-shift cylinder and tilt jack with new bushings and seals, and replace worn skid plates and pivot pins on the four-skid chassis as a set rather than one at a time.

Seasonal & Environment Servicing

Cold, abrasive, and wet jobsites hit the PC4's exposed mechanical parts hardest. In freezing weather, grease the hand-crank depth screw, tilt jack, and side-shift rails more often, since stiffened grease slows manual adjustment and can crack a forced thread. On abrasive reclaim or concrete work, check bits and holders more frequently, since wear accelerates. After wet or muddy jobs, rinse packed debris from the skid plates and side-shift slides, and dry hydraulic couplers before storage to keep moisture out of the carrier's circuit.

PC4 attachments & work tools

Machine type and class

PC4 is a standard-flow cold planer (asphalt/concrete milling drum) built for Cat skid steer loaders, compact track loaders, compact wheel loaders, and backhoe loaders. It sits in the legacy small-planer lineup (PC3/PC4/PC6/PC9), later superseded on price lists by the PC104/PC105/PC204/PC205/PC305 naming scheme, though sources do not explicitly document a PC4-to-PC104 succession.

Drum width and depth capacity

Max drum (working) width is about 406 mm (16 in), wider than the PC3's 305 mm (12 in) drum. As a standard-flow, utility-planing unit it cuts to roughly 51 mm (2 in) depth in asphalt and about 10 mm (0.38 in) in concrete.

Drive and hydraulic requirement

Drum drive is direct, using a variable-speed, unidirectional gerotor-style hydraulic motor sized for standard-flow host circuits. PC4 runs on standard-flow hydraulics like the PC3; the larger PC6 and PC9 in the same family step up to high-flow circuits.

Depth and tilt adjustment

Depth and tilt on the PC4 are manually/mechanically adjusted per side rather than hydraulically actuated, matching the entry-level position of this model in the family; independent left/right depth control lets the operator set each skid separately.

Side shift

Hydraulic side shift is standard on the PC4, giving close-in planing flexibility along curbs, walls, and other obstructions without repositioning the host machine.

Chassis and ground contact

The chassis rides on four pivoting skids that keep a stable cutting platform, reduce milled-material pickup, limit ground bearing pressure, and allow smooth travel between cuts.

Coupler and mounting system

Mounts to the host machine through Cat's standard skid steer quick-coupler/mounting-plate interface; hydraulic connections use flat-face quick couplers shared across the PC3, PC4, PC6, and PC9 family for quick, clean attach/detach.

Typical applications

Sized for small residential and commercial paving jobs: milling bumps or surface imperfections ahead of resurfacing, removing cracked or deteriorated pavement, stripping traffic-lane markings, and utility work where weight restrictions rule out a dedicated milling machine.

All PC4 assemblies by section

Every catalogued assembly group for the Caterpillar PC4. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Frame And Body
165-5336 Frame Gp-Cold Planer -Rear
02***87Fitting-Grease; (Universal Joint)6
09***66Bolt; (M8x1.25x75-mm)2
14***66Skid As2
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149-3276 Frame Gp-Cold Planer -Front
02***87Fitting-Grease; (Universal Joint)2
03***53Ring-Retaining2
14***60Housing As1
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165-5338 Frame Gp-Cold Planer -Front
02***87Fitting-Grease; (Universal Joint)2
03***53Ring-Retaining2
14***66Skid As2
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147-6784 Frame Gp-Cold Planer -Rear
02***87Fitting-Grease; (Universal Joint)6
09***66Bolt; (M8x1.25x75-mm)2
14***66Skid As2
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Hydraulic System
147-6781 Cylinder Gp-Hydraulic
00***14Ring-Retaining; (Internal)1
14***81Cylinder Group-Hydraulic1
16***77Kit-Seal1
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165-9896 Hydraulic Ar
14***81Cylinder Group-Hydraulic1
14***83Lines Group-Connecting1
14***84Manifold Group-Control1
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149-8883 Lines Gp-Connecting
14***83Lines Group-Connecting1
15***94Coupler As-Quick Disconnect; (Female)(Quick Disconnect)1
15***95Fitting As; (Quick Disconnect, Male)1
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144-9743 Motor Gp-Gerotor
11***36Kit-Seal1
14***43Motor Group-Gerotor1
16***88Key1
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147-6778 Motor Gp-Gerotor
11***36Kit-Seal1
14***78Motor Group-Gerotor1
16***88Key1
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163-1891 Valve Gp-Check
16***89Valve Group-Check1
16***91Valve Group-Check1
17***63Kit-Seal1
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Service Equipment And Supplies
165-5344 Plate & Film Gp
12***56Film; (Warning) (No Step) (On Top Of Hood Behind Cab On Each Side) (On Each Fender Flare)1
15***62Film-Information; (Tie-Down Location)4
15***35Film-Warning; (Crush Hazard, Stay Back)1
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165-5345 Plate & Film Gp
12***56Film; (Warning) (No Step) (On Top Of Hood Behind Cab On Each Side) (On Each Fender Flare)1
15***62Film-Information; (Tie-Down Location)4
15***35Film-Warning; (Crush Hazard, Stay Back)1
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Work Tool Arrangement
149-7669 Cold Planer Ar
14***83Drive Group-Cold Planer1
14***84Frame Group-Cold Planer; -Rear1
14***76Frame Group-Cold Planer; -Front1
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165-5334 Cold Planer Ar
16***34Cold Planer Ar1
16***35Drive Group-Cold Planer1
16***36Frame Group-Cold Planer; -Rear1
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Work Tools
144-9764 Adjustment Gp-Angle
02***87Fitting-Grease; (Universal Joint)4
14***64Adjustment Group-Angle1
16***97Handle1
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147-3151 Adjustment Gp-Depth
02***87Fitting-Grease; (Universal Joint)1
14***51Adjustment Group-Depth1
16***92Handle1
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165-5340 Adjustment Gp-Depth
02***87Fitting-Grease; (Universal Joint)1
16***92Handle1
16***93Boss1
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165-5335 Drive Gp-Cold Planer
01***15Setscrew-Socket; (1/2-13x0.5-In)(1/2 Thd)2
14***07Hub1
14***78Motor Group-Gerotor1
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147-6783 Drive Gp-Cold Planer
01***15Setscrew-Socket; (1/2-13x0.5-In)(1/2 Thd)2
14***07Hub1
14***43Motor Group-Gerotor1
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149-7666 Drum Gp-Cold Planer
11***26Bit As-Cutter; (Standard)50
14***63Bit As-Cutting; (Concrete)50
14***66Drum Group-Cold Planer1
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165-5342 Drum Gp-Cold Planer
11***26Bit As-Cutter; (Standard)28
14***63Bit As-Cutting; (Concrete)28
15***55Stud10
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165-5354 Drum Gp-Cold Planer
11***26Bit As-Cutter; (Standard)11
14***63Bit As-Cutting; (Concrete)11
15***55Stud6
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165-5356 Drum Gp-Cold Planer
11***26Bit As-Cutter; (Standard)11
14***63Bit As-Cutting; (Concrete)11
15***55Stud6
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165-5353 Drum Gp-Cold Planer
11***26Bit As-Cutter; (Standard)20
14***63Bit As-Cutting; (Concrete)20
15***55Stud6
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206-2567 Kit-Water Spray
00***86Connector-Hose (1/4-18nptf Thd)2
12***56Clamp-Hose10
17***92Coupling1
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172-3848 Kit-Water Spray
00***86Connector-Hose (1/4-18nptf Thd)1
12***56Clamp-Hose1
17***48Kit-Water Spray1
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PC4 serial number reference

The PC4 is a passive skid-steer cold-planer attachment with no engine or ECM of its own, so there is no engine PIN to cross-check. It is the standard-flow sibling to the PC3, with a larger 406 mm (16 in) max drum width versus the PC3's 305 mm (12 in), and runs on Cat skid steer standard-flow hydraulics through a direct-drive gerotor motor with manual ratcheting-screw-jack tilt and hand-crank depth control. The ID/PIN plate is riveted to the planer frame or housing near the mounting plate. Read the first three characters as the serial prefix (model/build identifier) and the remaining digits as the unit sequence number.

PrefixIdentifies
ACCPC4 Cold Planer, standard-flow skid steer attachment

Frequently asked questions

Does the Cat PC4 cold planer have its own engine?

No. The PC4 is a passive work-tool attachment with no engine or ECM of its own. A direct-drive, variable-speed gerotor hydraulic motor turns the drum, powered entirely by the host carrier's standard-flow hydraulic circuit, typically a skid steer, compact track loader, or backhoe loader supplying roughly 53-83 L/min at 172-227 bar.

What is the operating weight of the Cat PC4 cold planer?

The PC4 weighs about 522 kg (1150 lb) on its own, without a carrier. That makes it the larger of Cat's two standard-flow legacy cold planers, heavier than the narrower PC3 and well under the high-flow PC6 and PC9.

What replaced the Cat PC4 cold planer?

No confirmed direct successor to the legacy PC4 is documented. Cat's current PC104-PC412 cold-planer line is a separate, later product family with its own mounting and hydraulic specs; it should not be treated as a documented replacement for the PC3/PC4 generation.

What PC4 owners discuss

How does the PC4's hydraulic motor differ from Cat's high-flow cold planers, and what does that mean day to day?
The standard-flow line the PC4 belongs to runs a variable-speed, uni-directional gerotor motor, not the radial-piston motor fitted to high-flow and XHP planers. A gerotor motor delivers plenty of drum torque within its rated flow window but tops out on cutting rate in deeper or harder cuts compared with a piston-motor unit, the same trade-off as its PC3 sibling. Owners note the gerotor circuit is simpler and cheaper to service, but pushing it past its rated flow or pressure just stalls the drum instead of speeding up the cut.
What carrier hydraulic flow does a PC4 actually need, and what happens if it's mismatched?
Standard-flow cold planers in this class want roughly 45-114 L/min (12-30 GPM) at up to about 250 bar (3625 psi), varies by configuration and host machine. Running a high-flow-rated planer on a low-flow carrier, or a standard-flow unit on a circuit set too hot, is a recurring complaint: drum stall under load, ragged cut depth, and accelerated motor wear. Confirm the tool's rated flow/pressure window against the carrier's auxiliary hydraulic spec before buying or renting; a shop can check actual delivered flow on a meter rather than trusting the machine's dash rating alone.
Why do the cutting bits wear unevenly, and how do owners stretch bit life?
The outer bits on the drum take the brunt of the pavement edge and wear first, and each bit is meant to spin freely in its holder so wear stays even around the tip. When dirt and milling debris pack the holder and stop that rotation, a flat spot forms fast and the bit dulls well short of its normal service life. Regular practice is to check for free rotation and swap or re-rotate inner and outer bits as they wear, clean holders out each shift, and keep the drum off exposed rebar or iron grates, which chew a bit tip out of round almost immediately.
The depth (skid) shoes look worn or won't hold a consistent setting - what's going on?
The graduated skid shoes riding the pavement at each end of the drum set milling depth, and they need regular grease at the pivot points and side-shift rods or they gall and stick, throwing depth off from one side to the other. Community guidance is to get the drum turning before easing down to depth rather than dropping onto the surface from a stop, and to wipe off excess grease so it doesn't collect grit that speeds up shoe wear. Uneven wear side to side on the shoes is a common tell of a depth or tilt problem and worth checking with the drum set level.
What should be checked on the quick couplers and hoses before and after a job?
Flat-face couplers are the preferred setup now because they seal without oil loss on disconnect and keep contamination out of the circuit, while older ball-style couplers are more prone to weeping O-rings and debris ingress. Wipe both coupler faces clean before hookup and keep dust caps on in storage; after a job, inspect hoses for cracking, abrasion, or a seeping coupler face since milling grit is hard on seals. Always use the carrier's pressure-release function to bleed trapped pressure before forcing a stuck coupler apart - if a coupler won't relieve cleanly or a hose shows bulging, have your dealer verify the circuit before continuing to use it.
What's the biggest wear item tied to running a cold planer regularly, if not the attachment itself?
Because the planer loads the carrier hard at the cut and pushes weight forward onto the milled surface, owners report cold-planer duty is rough on the host machine's tires and tracks - fast wear and cuts from the freshly milled surface are common enough that some operators dedicate a unit with solid or foam-filled tires to planer work. This is carrier wear rather than a PC4 fault, but it belongs in the cost-of-ownership math for anyone running planer jobs regularly.
What should I check when buying a used PC4?
Walk the full drum for even bit height and confirm every bit still rotates freely in its holder; flat-worn or seized bits mean the previous owner wasn't rotating them and the holders may need attention. Check the drum by hand for runout or wobble and feel for play at the motor coupling and drive-end bearing. Inspect both skid shoes for even wear and cycle the depth-adjustment linkage through its full range checking for binding. Connect and disconnect the hydraulic couplers to confirm a clean, drip-free seal and look over hoses for cracking near the mount plate. Confirm the flow/pressure rating tagged on the unit actually matches your carrier's standard-flow circuit before committing to the purchase. Any drum bearing play or motor case-drain seepage found during this check is worth resolving before the unit goes into production work - have your dealer verify motor and bearing condition on a used PC4 before relying on it for daily use.

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

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