Caterpillarwork toolcold planer

Caterpillar PC404

Maintenance schedule, common problems & OEM parts breakdown

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The PC404 is a passive, carrier-powered cold planer work tool built for small-scale asphalt and concrete milling. It weighs about 680 kg (1,500 lb) as a standalone attachment, cuts to a maximum depth of 125 mm (4.9 in), and mills a path 450 mm (17.7 in) wide. It carries no engine, no ECM, and no onboard fluid system of its own; a direct-drive, uni-directional gerotor-style hydraulic motor turns the cutting drum entirely off the host machine's standard-flow hydraulic circuit. Mechanical self-leveling holds the drum at a constant cutting depth through roughly 130 degrees of float, and the drum runs conical bits as the standard cutting pattern, with heavier-duty asphalt and concrete bit options available. It attaches through a standard skid-steer-style quick-coupler and mounting plate and is rated to run on Cat skid steer loaders, compact track loaders, compact wheel loaders, and backhoe loaders.

Because the PC404 has no engine, no serial-prefix-tracked driveline, and no documented generational split, it sits in the used and parts market as a single-purpose milling attachment rather than a machine platform with a succession story. No confirmed predecessor or successor nameplate ties directly to the PC404; it occupies the standard-flow, mid-size slot in Cat's cold-planer lineup, between smaller compact units and the larger high-flow planers built for bigger loaders and track loaders. Resale and parts demand track wear-part churn far more than hour-meter age: bits and bit holders, skid plates, drum bearings and seals, and the drive motor turn over repeatedly across the tool's working life, while the coupler geometry shared across Cat's compact work-tool line keeps a broad pool of carrier owners in the market for it, including buyers running it on non-Cat carriers through an adapter plate.

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 PC404 specifications

Engine

Power sourceNo onboard engine. PC404 is a hydraulically driven work tool powered by the host carrier's hydraulic system via a direct-drive, variable-speed, uni-directional gerotor-style hydraulic motor.

Weights

Operating weight680 kg (1,499 lb / approx. 1,500 lb)

Dimensions

Overall length950 mm (37.4 in)
Overall width828 mm (32.6 in)
Overall height1,030 mm (40.6 in)
Working width / max. drum width450 mm (17.7 in)

Performance

Maximum cutting depth125 mm (4.9 in); manual depth control allows planing to approximately 127 mm (5 in)
Drum rotation130 degrees of rotation for the cutting head, for unrestricted planing angle
Depth controlSelf-leveling design levels automatically when set on the ground, for consistent depth control without operator adjustment
Bit typeStandard conical bits, asphalt/concrete duty
Carrier compatibilityMounts to skid steer loaders, compact track loaders, compact wheel loaders, and backhoe loaders

Service capacities (summary)

Required hydraulic flow80-160 L/min (21-42 gpm), standard-flow circuit
Optimal hydraulic pressure160-240 bar (2,320-3,480 psi)
Onboard fluidsNo dedicated fuel, engine oil, or cooling system; the work tool draws hydraulic power from the carrier machine and has no independent service capacities.

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

PC404 fluids & capacities

SystemCapacityRecommended fluid
Grease points (drum bearings, pivot/leveling linkage, coupler pins)Not a filled reservoir — hand-applied at each fitting per lubrication schedule, no listed fill volumeCat Multipurpose Grease (Cat MPGM), NLGI 2. Serviceable roughly -30 to 40 C (-22 to 104 F) without moly additive; use a moly-based multipurpose grease for heavier-load pins if the standard grade is unavailable

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

Caterpillar PC404 maintenance schedule

Service intervalTasks
Every 10 h
  • Inspect drum bits for chipping, flats, or missing carbide tips before each shift; rotate or replace as wear pattern dictates
  • Check skid plates for wear and confirm they still ride flat and parallel to the ground
  • Wipe down and visually check the quick-attach mounting plate and coupler pins for cracks, elongation, or loose hardware
  • Inspect hydraulic hoses, quick-disconnect couplers, and fittings for leaks, abrasion, or kinking before hookup to the carrier
  • Clear packed spoil and debris from the drum housing, bit holders, and skid plate mounts weekly to keep cutting geometry consistent
  • Grease the self-leveling linkage and drum bearing pivot points on the weekly interval
Every 250 h
  • Torque-check mounting plate and coupler retaining hardware
  • Inspect the drive motor shaft seal area for hydraulic seepage or staining
  • Check drum bearing play and end float by hand with the drum disengaged
  • Inspect self-leveling linkage bushings and pins for developing play
  • Confirm hose guides and routing clips are intact so lines cannot rub against the rotating drum housing
Every 500 h
  • Inspect the gerotor drive motor coupling for spline wear or backlash
  • Check drum housing and side plates for cracks or weld fatigue from repeated impact loading
  • Remove and inspect bit holders, replacing any that no longer retain bits securely
  • Re-torque all drum-to-motor and frame fasteners to spec
  • Check the host carrier's hydraulic filter and fluid condition, since the tool draws its entire power supply from that circuit
Every 1,000 h
  • Pull the drum drive motor for internal inspection if cutting speed or torque has dropped under normal carrier flow
  • Inspect and repack or replace drum shaft bearings and seals
  • Replace self-leveling arm pivot bushings if play exceeds allowable limits
  • Inspect structural welds at the skid plate mounts and frame for fatigue cracking
  • Check quick-coupler wear plates and pins for bore elongation, replacing as needed
Every 2,000 h
  • Rebuild or exchange the drum drive motor if seal or spline wear was confirmed at the prior inspection
  • Replace drum shaft bearings and seals as a matched set
  • Replace self-leveling linkage pins and bushings as a set rather than individually
  • Carry out a full structural check of the frame, drum housing, and mounting plate, repairing or retiring any fatigued section
  • Recoat the drum housing and skid plates after major rebuild work to protect against corrosion
Every 3,000 h
  • Evaluate the drum core for wear beyond serviceable limits and replace the complete core if bit-holder wear has become uneven
  • Replace the drive motor as an exchange unit rather than a field rebuild once output has degraded past acceptable range
  • Replace the attachment's hydraulic hoses as a set regardless of visual condition given accumulated flex-fatigue exposure
  • Inspect and refurbish or replace the mounting plate assembly if repeated coupler cycling has enlarged the pin bores

Servicing the PC404 beyond the schedule

Predictive Maintenance & Fluid Analysis

The PC404 carries no reservoir, filter, or ECM of its own, so predictive care means watching the host carrier's hydraulic system instead. Sample and trend the carrier's hydraulic fluid on schedule; the gerotor drive motor sheds fine metallic wear debris under sustained milling load that surfaces in fluid analysis long before it shows up as an external leak. Track return-line filter condition and case-drain temperature at the coupler, and treat any drop in cutting speed or drum torque at normal carrier flow as an early motor-wear signal worth acting on.

Corrective & Common Repairs

Most PC404 repairs center on the drum. Chipped, dull, or missing conical bits and worn bit holders are the highest-frequency fix and the first cause of rough surface texture or drum vibration. Worn skid plates let cutting depth wander and should be replaced together, not one at a time. Gerotor motor shaft-seal leaks or spline wear show up as reduced drum torque or hydraulic weep at the motor face and typically call for motor exchange rather than a field teardown. Cracked mounting-plate hardware from coupler shock load is the other recurring repair.

Overhaul & Rebuild Points

A full PC404 overhaul centers on three wear groups: the gerotor drive motor's spline, shaft seal, and internal rotor set; the drum shaft bearings and seals that absorb milling-impact loads; and the self-leveling linkage pins and bushings that hold cutting depth constant through the drum's float range. Rebuild triggers are bearing end-float beyond spec, linkage play that lets the drum chatter under cut, and motor output loss that persists at normal carrier hydraulic flow. Replace each wear group together rather than swapping individual pieces.

Seasonal & Environment Servicing

Cold starts stress the carrier's hydraulic oil more than the tool itself; let the carrier's hydraulic system warm before engaging the drum in low temperatures to keep the gerotor motor from cavitating on thick, cold oil. In hot, dusty milling work, clear packed spoil from the drum housing and skid plate mounts frequently, since abrasive buildup accelerates bit and skid-plate wear. Rinse the housing and coupler before extended storage to stop corrosion and prevent the mounting pins from seizing between jobs.

PC404 attachments & work tools

Cold planer cutting unit (the PC404 itself)

The PC404 is a compact cold planer work tool, not a carrier machine. Working width is 450 mm (17.7 in) with a maximum cutting depth of 125 mm (4.9 in). Unit weight is about 680 kg (1,499 lb) with overall dimensions near 950 mm long x 828 mm wide x 1030 mm high (37.4 x 32.6 x 40.6 in).

Carrier compatibility

Sized for Cat skid steer loaders, compact track loaders, compact wheel loaders, and backhoe loaders. It targets small residential and commercial paving jobs: milling surface imperfections before resurfacing, removing deteriorated pavement, and stripping traffic lane markings.

Mounting / coupler system

Attaches through the carrier's standard skid-steer-style quick-attach mounting plate, consistent with the rest of the compact Cat cold planer line. Dealer literature does not spell out a distinct coupler part or pin pattern for this model, so confirm plate compatibility against the specific carrier before ordering.

Hydraulic requirement

Runs on the carrier's standard-flow auxiliary hydraulic circuit, roughly 80-160 L/min (21-42 gal/min) at 160-240 bar (2,320-3,480 psi). A direct-drive, variable-speed, uni-directional gerotor-style hydraulic motor drives the drum, so no separate high-flow kit is called for.

Bit / drum configuration

Ships with standard conical asphalt/concrete carbide bits on a fixed 450 mm (17.7 in) wide drum. Dealer pages do not document alternate bit patterns or drum-width options specific to the PC404, unlike some larger cold planer siblings.

Depth control and self-leveling

Self-leveling design holds a constant planing depth once set on the ground, improving spoil retention without operator adjustment. Manual depth control lets the operator plane up to about 125 mm (5 in), and the tool head offers roughly 130 degrees of rotation for positioning.

Water/dust suppression kit

Not documented as a factory option for the PC404 in dealer literature. Other models in the Cat cold planer lineup are offered in a "With Water" configuration for dust suppression, but no source ties that option to the PC404 specifically, so treat it as unavailable unless a dealer confirms otherwise.

Product line / size class context

The PC404 sits toward the compact end of Cat's cold planer range, which spans smaller and larger siblings sized for everything from mini/compact carriers up to larger loaders. Specs, bit types, and options do not carry over between siblings; treat each model's cutting width, depth, and hydraulic range as distinct.

All PC404 assemblies by section

Every catalogued assembly group for the Caterpillar PC404. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Frame And Body
232-0510 Frame Ar-Cold Planer
23***10Frame Ar-Cold Planer1
23***11Frame Group-Cold Planer1
23***24Adjustment Group-Depth1
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232-0511 Frame Gp-Cold Planer
13***40Locknut; (M8x1.25-Thd)1
21***38Bearing4
23***11Frame Group-Cold Planer1
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219-5483 Mounting Gp-Cold Planer
21***83Mounting Group-Cold Planer1
23***82Bracket As-Mounting1
7X***63Bolt-Plt; (M20 X 2.5 X 60)6
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Hydraulic System
219-5471 Hydraulic Ar
19***12Seal-O-Ring2
21***71Hydraulic Ar1
21***73Valve Group-Check1
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219-5484 Lines Gp-Connecting
10***01Fitting; (Quick Disconnect, Female)1
10***06Fitting; (Quick Disconnect, Male)1
14***39Connector As.4
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219-5472 Motor Gp-Gerotor
21***72Motor Group-Gerotor1
22***33Screw6
23***59Kit-Seal; (Motor)1
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Service Equipment And Supplies
234-6649 Film Gp
15***35Film-Warning; (Crush Hazard, Stay Back)1
15***36Film-Warning; (Read Operation Manual)1
15***40Film-Warning; (No Clrn, Flying Obj, Stay Back)2
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Work Tool Arrangement
219-5470 Cold Planer Ar
21***70Cold Planer Ar1
21***71Hydraulic Ar1
21***83Mounting Group-Cold Planer1
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Work Tools
232-0524 Adjustment Gp-Depth
09***91Pin - Spring1
21***24Bushing1
21***26Pin1
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219-5481 Bracket As-Mounting
21***81Bracket As-Mounting1
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219-5482 Bracket As-Mounting -Jcb Linkage
21***82Bracket As-Mounting; -Jcb Linkage1
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232-0527 Drive Gp-Cold Planer
21***72Motor Group-Gerotor1
21***87Bolt-Special1
22***08Nut; (M14x1.5-Thd)10
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232-0525 Drum Gp-Cold Planer
22***71Bit As-Cutting; (Standard)48
22***08Holder-Bit48
22***40Bit As-Cutter; (Concrete Applications)48
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Frequently asked questions

What powers the Cat PC404 cold planer?

The PC404 has no engine or ECM of its own. It runs entirely off the host carrier's hydraulic system through a standard-flow circuit, which drives a direct-drive, gerotor-style hydraulic motor that turns the cutting drum.

What is the operating weight of the PC404?

The PC404 weighs about 680 kg (1,500 lb) as a standalone attachment, not counting the host carrier it mounts to.

What replaced the PC404, or what compares to it in Cat's lineup?

No documented direct successor or generational replacement is tied to the PC404 nameplate. It remains a current standard-flow, mid-size option in Cat's cold-planer attachment lineup, sitting between smaller compact planers and the larger high-flow units built for bigger skid steers and track loaders.

What PC404 owners discuss

What hydraulic flow does the PC404 actually need to cut properly?
The PC404 has no engine of its own, so cutting power comes entirely from the host carrier's auxiliary hydraulic circuit driving a direct-drive, uni-directional, variable-speed gerotor-style motor. Operators consistently report that running below the carrier's rated flow window starves the drum and lets it stall or bog down mid-cut, while running above the window pushes excess oil across the motor and generates heat the attachment cannot shed. The practical fix reported by users is matching the tool to a skid steer, CTL, compact wheel loader, or backhoe loader whose factory auxiliary flow sits within the PC404's specified range rather than assuming any high-flow circuit will do.
How does the self-leveling and depth control behave day to day?
The PC404 levels itself once set on the ground and offers manual depth control up to about 125 mm (4.9 in), with side plates that pivot independently to track uneven pavement. Consistent hydraulic pressure and flow are what keep the cut depth even across a pass; owners note that flow that surges or drops mid-cut (from a marginal carrier pump or a partly restricted hose) shows up as a wavy or inconsistent milling depth rather than a clean, uniform strip.
What wear pattern shows up on the drum and cutting bits?
Conical bits should be checked at routine intervals to confirm they still spin freely in the holder; a bit that has gone flat, chipped, or seized is due for replacement, and community experience with this class of drum warns that a seized bit left in service will quickly gouge the holder pocket and the drum housing around it. Outer-row bits tend to show wear first since they do the most work at the cut edges, and bit life on asphalt runs far longer than on concrete because of the difference in abrasiveness. Have your dealer verify drum and holder condition before returning a re-picked unit to service, since a damaged holder can eject a bit at speed.
Are the side plates and skid shoes a wear item to plan for?
Yes. The side/skid plates are wear-resistant and pivot to follow the ground contour, and the lower section that rides on the pavement is the part that wears down and is replaced separately from the rest of the plate. Operators flag that a plate worn unevenly or knocked out of flat will throw off cut depth side to side even when the drum and hydraulics are working correctly, so it is worth checking plate flatness whenever depth control looks inconsistent.
Does the PC404 have any electrical or sensor issues to worry about?
There is no engine control module or sensor network on this tool since it is a passive, carrier-powered attachment. The one electrical component is the plug-and-play harness and quick-coupler connector that lets the in-cab controls operate the leveling/depth cylinders. Across this class of cold-planer attachment, the recurring complaint is corroded or bent pins in that connector causing the leveling controls to stop responding, which reads like an electrical fault but is really a dirty or damaged coupler needing cleaning or pin replacement rather than a diagnostic-level failure.
What does a failing hydraulic motor look like on this kind of attachment?
With a gerotor-style motor, the classic warning signs described by operators are the drum spinning freely with no load but bogging or stalling as soon as it bites into pavement (a sign of internal leakage past a worn rotor set), a grinding or whining noise pointing to bearing wear or cavitation, and return oil that runs consistently hot, which usually traces back to operating outside the attachment's rated flow window rather than the motor itself. Because distinguishing a worn motor from a flow-mismatch problem requires a case-drain flow test, have your dealer verify the diagnosis before authorizing a motor replacement.
What should I check before buying a used PC404?
Inspect the quick-coupler and electrical harness pins for corrosion or bending, confirm every bit spins freely in its holder with no flat spots or seizure, and look inside the drum housing for gouging that would indicate a bit was run seized. Check the side/skid plates for flatness and remaining wear material and confirm they pivot freely. Cycle the self-leveling and manual depth control and watch for a smooth, steady depth change rather than any stutter or lag. Since the attachment carries no hour meter of its own, ask for the host carrier's usage records as the best available proxy for how hard the tool has been run.

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

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