Caterpillar PP120
Maintenance schedule, common problems & OEM parts breakdown
The Caterpillar PP120 is not a carrier machine in the usual sense. It is a self-contained, skid- or tow-mounted hydraulic power pack: a small engine driving a gear pump and reservoir, built to supply hydraulic flow to a separate demolition hammer arrangement rather than to move or dig anything itself. In Cat's own parts documentation the power pack (serial prefix ETB) is paired with a hammer/breaker arrangement badged PH126 (serial prefix TJR), sold both under the Cat brand and rebadged for Hewden, a UK plant-hire company. No engine make or model, horsepower rating, operating weight, dimensions or hydraulic flow and pressure figures are published for the unit; the only confirmed technical detail is that it runs on biodegradable hydraulic oil per its own identification decal. Serial prefixes place production in the mid-2000s, and no documented predecessor or successor exists for this specific power-pack-and-hammer combination.
Because the PP120 was built in low volume as a job-site accessory rather than a mainstream product line, there is no evidence of a generational split, engine change, or spec revision across its production run; the main documented variation is branding, Cat-badged versus Hewden-badged, over the same hardware. That thin paper trail is exactly why the unit matters in today's used and parts market: buyers and parts counters encounter it rarely, cannot pull a spec sheet or owner's manual, and must lean on serial-prefix identification (ETB for the power pack, TJR for the hammer arrangement) and dealer lookup to confirm fitment before ordering hoses, filters or hammer wear parts. Anyone sourcing this unit second-hand should treat every spec beyond the confirmed fluid type as unverified until checked against the physical machine and its dealer parts lookup.
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 PP120 specifications
Engine
| Configuration | Self-contained engine-driven hydraulic power pack (cart-mounted, engine plus gear pump plus reservoir) built to run a separate hydraulic hand tool through quick-disconnect hoses. No published engine model, gross/net power, displacement, cylinder count, or emissions tier for this unit. |
| Speed control | Engine speed-control cylinder group described in the parts catalog as power-on-demand, meaning engine speed responds to hydraulic load rather than running at a fixed governed speed. No RPM figures published. |
| Cooling | Engine-driven blower wheel and cowling confirm air cooling. No radiator or coolant-capacity data published. |
Weights
| Operating weight | Not published for this power pack. No factory spec sheet or dealer listing gives a shipping or operating weight for this configuration. |
Dimensions
| Transport dimensions | Not published. The unit rides on its own frame with mounted wheels and lift handles for jobsite towing/carrying, but no length, width, or height figures are documented. |
Performance
| Hydraulic circuit | Feeds a separate hydraulic tool (hammer/breaker arrangement) through quick-disconnect couplers with a control valve, thermostat valve, relief valve, and oil cooler in the manifold. No flow rate or pressure figures published. |
| Travel/gradeability | Not applicable — this is a stationary/towed power pack, not a self-propelled machine. No travel speed or gradeability specs exist. |
Service capacities (summary)
| Hydraulic system | Has a dedicated hydraulic oil tank and cooler platform with sight glass and biodegradable hydraulic oil provision, but no published tank capacity figure. |
| Fuel and engine oil | Not published. No fuel tank or engine oil capacity figures are documented for this power pack. |
Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.
PP120 fluids & capacities
| System | Capacity | Recommended fluid |
|---|---|---|
| Hydraulic system (tank and oil cooler, power-pack circuit) | Not published for this model — no factory refill figure found in circulation; the platform group pairs a hydraulic tank with an oil cooler and filter, so expect a modest reservoir sized to a small self-contained power pack, not a full excavator system | Cat BIO HYDO (HEES biodegradable hydraulic oil) — the machine's own hydraulic-oil identification decal calls out a biodegradable hydraulic fluid, so this is the factory-specified type rather than conventional Cat HYDO/TDTO. No published cold-weather viscosity grade split is available for this unit |
| Power-pack engine crankcase (with filter) | Not published — this is a small self-contained engine driving the gear pump for the power pack, not a Cat highway/machine engine, and no OMM with a refill figure could be located | Not confirmed. The engine's make and displacement are not documented in available literature for the PP120; do not assume a Cat DEO recommendation without verifying engine identity against the plate on the unit |
| Fuel tank | Not published — a fuel identification decal is specified in the parts catalog confirming a diesel fuel tank on the power-pack frame, but no tank volume is documented | Diesel fuel (decal-confirmed on the unit); no cold-weather blend guidance published for this model |
| Grease points | No lubrication fittings or grease points are called out in the documented parts breakdown for this unit | Not applicable / not documented — treat as a sealed or self-lubricating power-pack and hammer assembly unless a grease fitting is found on the physical unit |
Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.
Caterpillar PP120 maintenance schedule
| Service interval | Tasks |
|---|---|
| Every 50 h |
|
| Every 250 h |
|
| Every 500 h |
|
| Every 1,000 h |
|
| Every 2,000 h |
|
| Every 4,000 h |
|
Servicing the PP120 beyond the schedule
Predictive Maintenance & Fluid Analysis
With no engine ECM or fault-code system documented on the PP120, condition monitoring rests on fluid sampling and visual inspection rather than diagnostic codes. Pull hydraulic oil samples on a regular interval and watch for water intrusion, particulate contamination or additive breakdown, especially since the unit runs a biodegradable hydraulic fluid that degrades differently than mineral oil. Track engine oil condition and air filter restriction closely given the small air-cooled powerplant, and log hose and coupling seepage before it becomes a failure.
Corrective & Common Repairs
Typical PP120 failures center on the hydraulic circuit and the hammer end rather than a drivetrain. Expect hose and quick-coupler leaks from field abuse, worn or elongated hammer tool pins and bushings from percussive loading, and coupling misalignment between the small engine and gear pump after repeated tow or transport. On the engine side, no-start complaints usually trace to fuel, ignition or air-intake fouling common to compact air-cooled units rather than anything electronic.
Overhaul & Rebuild Points
Rebuild work on the PP120 falls into three areas: the hydraulic pump and reservoir, the hammer's piston and tool-retention hardware, and the engine top end. Pump seals and reservoir breathers wear from continuous duty cycling; the hammer's front-head bushing and piston bore take the brunt of demolition loading and need periodic rebuild rather than one-time replacement; the engine should be overhauled on its own maker's schedule since no Cat-specific engine overhaul data exists for this unit.
Seasonal & Environment Servicing
Because the PP120 is a portable, often outdoor-stored unit, seasonal care matters more than on a cab-protected machine. Confirm the biodegradable hydraulic oil grade suits cold-weather viscosity needs before winter use, protect exposed hoses and the tow chassis from corrosion during outdoor storage, and step up air filter and intake screen servicing when working dusty demolition or quarry sites where the small engine draws contaminated air.
PP120 common service parts
| Part number | Part | Notes | |
|---|---|---|---|
| 274-6264 | Filter-Oil | Hydraulic service | Check fitment → |
Always confirm against your machine's serial number — cross-check any part in Heavy Parts AI before ordering.
PP120 attachments & work tools
Primary work tool - hand-held hydraulic breaker
The PP120 is a power pack built to drive one hand-held hydraulic hammer (breaker gun), not a carrier machine that swaps buckets or work tools. The hammer housing takes a single moil-point or chisel-type tool bit, held in with a spring-loaded lockpin and latch.
Hydraulic hose and quick-disconnect coupling
The pack and the hammer link through a male/female quick-disconnect fitting pair, with dust caps fitted whenever the tool is unhooked. Two slightly different connecting-line arrangements appear in the catalog - one for the base pack, one for the paired hammer set - so hose routing can vary a little by build.
Engine-driven hydraulic pump arrangement
An engine section drives a gear pump through a flexible coupling and spider, feeding the hammer through a control-and-filter manifold that carries a relief valve, thermostat valve, and hydraulic-oil cooler mounted on its own platform. No carrier-machine hookup is documented; the unit is meant to stand alone.
Hand control and power-on-demand throttle
A hydraulic hand-control lever group, with an adjustment screw and spring-loaded latch pins, triggers the hammer circuit. It pairs with an engine-speed-control cylinder built for power-on-demand operation, so the engine idles down when the hammer isn't firing and picks up speed when it is.
Wheeled frame and site mounting
The pack sits on a two-wheel frame with tow handles and a hydraulic-tank platform, built for towing or repositioning around a job site rather than for mounting to a carrier. No quick-hitch or coupler plate is documented for this unit.
Factory decal and branding configuration
Units left the factory with either a Cat-branded or a Hewden-branded plate-and-film set (Hewden being a UK plant-hire operator), each carrying matching identification film for the paired hammer plus the usual hydraulic-oil and safety-warning decals. Confirm which decal set applies to a given unit before ordering replacement film.
Attachment ecosystem - verify with dealer
Current dealer attachment guides and work-tool line sheets do not list a PP120 by name, and no public spec sheet gives flow rate, impact energy, or engine output for this pack. Treat any capacity or hammer-class figures for this unit as unconfirmed until checked against its own dealer or nameplate data.
All PP120 assemblies by section
Every catalogued assembly group for the Caterpillar PP120. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.
Frame And Body
274-6244 Cover Gp-Access
| 27***38 | Gasket-Seal | 2 |
| 27***44 | Cover Group-Access | 1 |
| 27***57 | Filler As-Oil | 1 |
274-6256 Frame Gp-Power Pack
| 27***28 | Frame As | 1 |
| 27***29 | Tube As | 1 |
| 27***43 | Handle | 2 |
274-5530 Platform Gp-Hyd Oil Tank & Clr
| 09***73 | Plug, Shipping | 1 |
| 26***84 | Spacer; (23x34x10-mm Thk) | 2 |
| 27***30 | Platform Group-Hydraulic Oil Tank & Clr | 1 |
Hydraulic System
275-0453 Body Gp-Valve
| 21***16 | Washer | 1 |
| 27***71 | Bolt-Socket Head | 1 |
| 27***72 | Ball | 1 |
275-0744 Control Gp-Hydraulic Hand
| 09***14 | Pin; (Spring) | 2 |
| 27***54 | Screw As-Adjustment | 1 |
| 27***56 | Cap-Nut | 1 |
274-6255 Lines Gp-Connecting
| 15***96 | Fitting As; (Quick Disconnect, Male)(Quick Disconnect) | 1 |
| 15***97 | Fitting As; (Quick Disconnect, Female) | 1 |
| 16***60 | Cap-Dust | 1 |
275-0743 Lines Gp-Connecting
| 15***96 | Fitting As; (Quick Disconnect, Male)(Quick Disconnect) | 1 |
| 15***97 | Fitting As; (Quick Disconnect, Female) | 1 |
| 16***60 | Cap-Dust | 1 |
277-8155 Lines Gp-Hydraulic
| 03***79 | Nipple; (Hose) | 1 |
| 09***88 | Clamp; (Hose) | 6 |
| 12***70 | Hose-Hydraulic; (9-In) | 1 |
274-6227 Manifold Gp-Control & Filter
| 03***79 | Nipple; (Hose) | 1 |
| 09***78 | Pin-Spring | 3 |
| 09***77 | Seal-O-Ring; (9.80mm Id) | 1 |
274-6240 Mounting Gp-Control
| 1G***59 | Clamp | 2 |
| 1R***96 | Bolt (35mm Long); (M6x1x35-mm) | 2 |
| 27***40 | Mounting Group-Control | 1 |
Service Equipment And Supplies
280-1957 Plate & Film Gp -Cat
| 13***10 | Film-Oil; (Biodegradable)(Hydraulic) | 1 |
| 16***89 | Tack-Fastener | 4 |
| 23***27 | Film-Identification; (Fuel) | 1 |
275-0746 Plate & Film Gp -Hewden
| 24***76 | Film-Warning; (Do Not Operate, Read Omm) | 1 |
| 27***46 | Plate & Film Group; -Hewden | 1 |
| 27***56 | Film-Identification; (Cat Ph126) | 2 |
280-1956 Plate & Film Gp -Cat
| 22***44 | Film-Warning; -Universal | 1 |
| 27***16 | Film-Warning; (Hot Surface, Hand Protection) | 1 |
| 27***36 | Film-Warning; (Eye, Ear, Foot Protn Required) | 1 |
276-8832 Plate & Film Gp -Hewden
| 13***10 | Film-Oil; (Biodegradable)(Hydraulic) | 1 |
| 23***27 | Film-Identification; (Fuel) | 1 |
| 24***76 | Film-Warning; (Do Not Operate, Read Omm) | 1 |
Work Tool Arrangement
280-1959 Hammer Ar-Hydraulic
| 16***89 | Tack-Fastener | 4 |
| 27***51 | Hammer Group-Hydraulic | 1 |
| 27***43 | Lines Group-Connecting | 1 |
272-6579 Hammer Ar-Hydraulic -Hewden
| 27***79 | Hammer Ar-Hydraulic; -Hewden | 1 |
| 27***51 | Hammer Group-Hydraulic | 1 |
| 27***43 | Lines Group-Connecting | 1 |
280-1960 Power Pack Ar
| 16***89 | Tack-Fastener | 4 |
| 27***30 | Platform Group-Hydraulic Oil Tank & Clr | 1 |
| 27***27 | Manifold Group-Control & Filter | 1 |
272-6580 Power Pack Ar -Hewden
| 27***80 | Power Pack Ar; -Hewden | 1 |
| 27***30 | Platform Group-Hydraulic Oil Tank & Clr | 1 |
| 27***27 | Manifold Group-Control & Filter | 1 |
Work Tools
274-6253 Engine Gp-Power Pack
| 27***32 | Cowling | 1 |
| 27***33 | Wheel-Blower | 1 |
| 27***34 | Spacer | 1 |
275-0451 Hammer Gp-Hydraulic
| 11***66 | Seal-O-Ring | 1 |
| 16***95 | Seal-U-Cup | 1 |
| 1T***04 | Ring-Retaining | 1 |
275-0745 Housing Gp-Hammer
| 09***94 | Pin-Spring | 1 |
| 12***81 | Bolt-Socket Head; (M10x1.5x55-mm) | 2 |
| 1K***66 | Spring-Compensator | 1 |
PP120 serial number reference
The PP120 is a two-piece system: an engine/pump power-pack frame plus a separate hammer head. Each piece carries its own small ID plate riveted or bolted to its frame rather than one machine-wide PIN plate. Read the plate for the arrangement number and the serial break stamped below it. The power-pack frame and the hammer head each show their own 3-letter-plus-digits serial block, tracked as separate assemblies even though sold as a matched set.
| Prefix | Identifies | Notes |
|---|---|---|
| ETB | Power Pack Arrangement (engine, frame, hydraulic tank/cooler, control manifold) - the PP120 power-pack unit itself | Self-contained engine-driven hydraulic pump unit that feeds a separate hammer through hose lines, so the carrier needs no auxiliary hydraulics. Covers the Cat-badged frame and the Hewden-rebadged version of the same frame. Starts the number sequence for this power pack line, dating to its mid-2000s introduction. Confirm exact serial break with your dealer for a specific unit. |
| TJR | Hammer Arrangement (breaker head, valve body, hand control, housing) matched to the PP120 power pack | Sold and serialed as a separate arrangement from the power-pack frame, documented in the same parts book and marketed as a power-pack-and-hammer combo. Covers the Cat-badged hammer arrangement and the Hewden-rebadged version. Confirm exact serial break with your dealer for a specific unit. |
Frequently asked questions
What engine powers the Caterpillar PP120?
No engine make, model or horsepower rating for the PP120 is published in any Cat documentation. The unit is a small self-contained power pack pairing an engine with a gear pump and hydraulic reservoir; confirm the specific engine fitted to your unit through your Cat dealer using the machine's serial number and prefix (ETB).
What is the operating weight of the Caterpillar PP120?
Operating weight is not published for the PP120. As a compact, skid- or tow-mounted power pack rather than a full carrier machine, it is documented only through Cat's parts book, which does not list weight, dimension or capacity figures. Check with a dealer or weigh the specific unit if this figure is needed.
What replaced the Caterpillar PP120?
No documented successor exists. The PP120 power pack and its paired PH126 hammer arrangement appear to have been a limited, job-specific product with no confirmed follow-on model in Cat's lineup. Treat any claimed replacement model with caution until verified through a dealer or an official Cat document.
What PP120 owners discuss
Is there much owner or mechanic discussion online about the PP120 specifically?
What engine quirks should an operator expect on a unit like this?
What hydraulic behaviors are typical for this kind of power pack and hammer arrangement?
Where does wear concentrate on the chassis since this isn't a tracked machine?
Does the PP120 have any real electrical or sensor issues to watch for?
What should a buyer check before purchasing a used PP120?
Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.
Need a specific PP120 part?
Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.