Caterpillarwork toolhammer

Caterpillar H55DS

Maintenance schedule, common problems & OEM parts breakdown

The Caterpillar H55DS is a hydraulic hammer (breaker) work tool, not a self-powered machine. It carries no engine, transmission, fuel tank, or cooling system of its own; it runs entirely off the host carrier's auxiliary hydraulic circuit. Cat sizes it for skid-steer and multi-terrain loaders and the 302.5C, 303C CR, and 303.5C CR mini excavators, in roughly the 2.5-4.5 t (5,500-9,900 lb) carrier class for pin-on mounting, with some flat-top setups rated up to about 6.0 t (13,200 lb). Working weight runs 199 kg (439 lb) pin-on or 250 kg (551 lb) flat-top, with an impact energy class of 678 J (500 ft-lb) and a 56 mm (2.2 in) tool shaft. It belongs to Cat's D-box generation of small hammers (H25D, H35D S, H45D S, H55D S, H65D S), offered in flat-top (bracket-mounted, dedicated quick coupler) and pin-on (pin-grabber-compatible) configurations, and it takes chisel, moil, spade, or compacting-plate tips for rock, concrete, demolition, or compaction work.

The 'Ds' suffix marks Cat's silenced version of this size class: the power cell sits isolation-mounted on urethane/nylon buffers instead of being clamped rigidly between metal side plates, cutting jobsite noise and vibration feedback into the carrier compared with a non-silenced hammer of the same size. This generation also runs a simplified internal parts count compared with the older hammer line it replaced, which shows up today mainly in how few routine wear items owners have to track, the tool bushing being the main one. Two serial-prefix production blocks tie specifically to this model, BWM (original run) and FTF (a later running-change series), and it shares one parts book with three sibling sizes built on the same platform, so confirming the full stamped serial against a parts lookup matters before ordering service parts. On the used market, that shared D-box platform keeps service support and tooling available well after this size's original production run, and a hammer's grease and reseal history matters more to resale value than raw hour count alone.

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 H55DS specifications

Engine

Engine	None fitted. The H55DS is a hydraulic hammer with no onboard engine, transmission, fuel tank, or cooling system. It runs entirely on the host excavator's hydraulic circuit.
Power source	Hydraulic, supplied through the carrier's auxiliary tool-control line (combined tool control, one-way auxiliary lines).

Weights

Working weight, pin-on	199 kg (439 lb), includes hammer, standard tool and mounting.
Working weight, flat-top	250 kg (551 lb), includes hammer, standard tool and mounting group.
Recommended carrier weight, pin-on	2.5-4.5 t (5,500-9,900 lb).
Recommended carrier weight, flat-top	2.5-6.0 t (5,500-13,200 lb).

Dimensions

Overall (housing) length, flat-top	827 mm (32.6 in).
Overall (housing) length, pin-on	997 mm (39.3 in).
Frontal width, flat-top	444 mm (17.5 in).
Frontal width, pin-on	429 mm (16.9 in).
Lateral width, flat-top	286 mm (11.3 in).
Lateral width, pin-on	300 mm (11.8 in).
Tool (chisel) diameter	56 mm (2.2 in).
Standard tool length	About 298-299 mm (11.7-11.8 in); actual exposed length varies with tool type (chisel, moil, spade, compacting plate).

Performance

Impact frequency (blow rate)	1,022-2,300 bpm.
Impact energy class	678 J (500 ft-lb).
Operating (hydraulic) pressure	170 bar (about 2,466 psi).
Acceptable oil flow	40-85 L/min (10.6-22.5 gpm).
Mounting configuration	Flat-top (bracket-mounted, dedicated quick coupler) or pin-on (integral mount, compatible with the pin-grabber quick coupler system).
Tool options	Chisel, moil, spade (parallel or transverse), or compacting plate, chosen by rock type and application.
Host carrier compatibility	Sized for the 302.5C, 303C CR and 303.5C CR mini hydraulic excavators; also offered on Cat skid-steer and multi-terrain loaders as a compact-carrier attachment.

Service capacities (summary)

Fuel tank	Not applicable, no onboard engine.
Hydraulic system	No dedicated reservoir. Draws flow and pressure from the host carrier's hydraulic system within the ranges listed under Performance.
Engine oil	Not applicable, no onboard engine.
Cooling system	Not applicable, no onboard engine or radiator; heat is carried away through the host machine's hydraulic oil.
Tool lubrication	Lower tool bushing needs regular grease; an auto-lube connection is provided for automatic greasing systems.

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

H55DS fluids & capacities

System	Capacity	Recommended fluid
Grease - tool bushing and retainer pin (lower bushing/tool interface)	Grease-only lubrication point; no fluid capacity in liters. Apply with a grease gun in the upright position with the tool pressed down (weight on the tool): 10 to 15 pump strokes per grease fitting, continuing until fresh grease purges at the gap between the tool and lower bushing. Grease before every shift (about every 2 hours of hammer operation); shorten to about once an hour in severe, abrasive, or wet conditions. If equipped with an auto-lube cartridge, check the cartridge level before operation and replace it once the low-level indicator shows.	Cat Hydraulic Hammer Paste (copper and graphite grease), formulated to resist seizing and heavy friction at the tool/bushing interface, with protection at contact temperatures up to about 1,093 degrees C (2,000 degrees F). This is the only grease Caterpillar recommends for the tool bushing on this hammer size range; no alternate climate-based viscosity grades are published because it is an extreme-pressure paste, not a viscosity-graded oil.

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

Caterpillar H55DS maintenance schedule

Service interval	Tasks
Every 2 h	Grease the tool bushing/retainer pin fitting with 10-15 gun strokes until fresh grease purges at the tool-to-bushing gap, before every shift or about every 2-3 hours of active hammering. Shorten the grease interval to about once an hour when working in severe, abrasive, or wet conditions. Check the auto-lube cartridge level before starting, if the hammer is fitted with one, and replace the cartridge once the low-level indicator shows. Inspect the tool and retainer pin for play or wobble before putting the hammer to work. Confirm the quick coupler or pin lock is fully seated and the carrier's auxiliary circuit is switched to breaker mode before triggering.
Every 600 h	Inspect the seal set and diaphragm and replace as needed, roughly every 600 hours or once a year, whichever comes first. Have your dealer verify the nitrogen pre-charge and perform any accumulator recharge; this is high-pressure work, not a field job. Check housing and mounting bracket fasteners for cracking, stretching, or loosening; retorque or replace as needed. Inspect the front head and tool holder for cracking or scoring. Measure tool bushing play against the service limit and rotate or replace the bushing once it's exceeded. Inspect hydraulic hoses and couplers at the tool connection for wear, weeping, or damage.

Service interval

Tasks

Every 2 h

Grease the tool bushing/retainer pin fitting with 10-15 gun strokes until fresh grease purges at the tool-to-bushing gap, before every shift or about every 2-3 hours of active hammering.
Shorten the grease interval to about once an hour when working in severe, abrasive, or wet conditions.
Check the auto-lube cartridge level before starting, if the hammer is fitted with one, and replace the cartridge once the low-level indicator shows.
Inspect the tool and retainer pin for play or wobble before putting the hammer to work.
Confirm the quick coupler or pin lock is fully seated and the carrier's auxiliary circuit is switched to breaker mode before triggering.

Every 600 h

Inspect the seal set and diaphragm and replace as needed, roughly every 600 hours or once a year, whichever comes first.
Have your dealer verify the nitrogen pre-charge and perform any accumulator recharge; this is high-pressure work, not a field job.
Check housing and mounting bracket fasteners for cracking, stretching, or loosening; retorque or replace as needed.
Inspect the front head and tool holder for cracking or scoring.
Measure tool bushing play against the service limit and rotate or replace the bushing once it's exceeded.
Inspect hydraulic hoses and couplers at the tool connection for wear, weeping, or damage.

Servicing the H55DS beyond the schedule

Predictive maintenance & fluid analysis

There's no oil reservoir or filter to sample on the H55DS; predictive care here means watching operating signs instead. Track grease consumption at the tool bushing fitting between top-ups: a fitting that won't take fresh grease, or purges much slower than normal, flags a closing gap or a worn bushing early. Log cycle rate and listen for hose bounce during operation; a falling blow rate or bouncing supply hose usually means nitrogen pre-charge is drifting down well before the diaphragm actually fails. Catching either trend early avoids an unplanned teardown.

Corrective & common repairs

Most H55DS repairs trace back to two habits: blank-firing and stretched grease intervals. Blank-firing dumps piston energy straight into the retainer pin and tool bushing with nothing loaded against the tool, cracking retainers and battering the bushing bore fast. Skipped or stretched grease intervals starve the tool-to-bushing interface, showing up as tool wobble and play. Before assuming a bigger fault, check the simple stuff first: a closed shutoff valve, an unseated coupler, or the carrier's circuit not switched to breaker mode all stop the hammer without internal damage.

Overhaul & rebuild points

Plan a reseal around the tool bushing, front head, and accumulator seals once tool play exceeds the service limit or oil weeping shows up around the accumulator. Cat's guidance calls for inspecting or replacing the seal set and diaphragm roughly every 600 hours or once a year, whichever comes first. Because the accumulator runs at very high pressure, have a dealer verify nitrogen pre-charge and handle any recharge. Check housing and mounting fasteners for cracking or stretching at the same time.

Seasonal & environment servicing

In wet, muddy, or highly abrasive rock and demolition work, shorten the tool bushing grease interval from the standard 2-3 hours down to about once an hour; the tool-to-bushing interface runs dry fast once fines or water wash the paste out. Wipe down and inspect the accumulator and hose connections more often in freezing conditions, since a sluggish diaphragm or brittle hose shows up first as hose bounce or a hesitating stroke. Keep the auto-lube cartridge, if fitted, topped up and check its level before every shift regardless of season.

H55DS attachments & work tools

Tool tip options

The H55Ds accepts interchangeable chisel, moil (point), spade, and compacting-plate tool tips on the same 56 mm (2.2 in) shaft, letting one hammer body cover rock seaming, general concrete/rock breaking, asphalt cutting, and soil compaction work.

Mounting system

The hammer uses integral top-mount construction, so no separate mounting bracket is needed when fitted to an excavator dipper. It is built to work with the Cat pin-grabber quick-coupler system for fast tool changes on excavators.

Coupler compatibility

On skid steer and multi-terrain loader carriers the H55Ds connects through the standard universal skid-steer quick-attach coupler rather than a pin-grabber coupler; on mini excavators it pins directly to the stick/link or through a compatible quick coupler.

Carrier weight class

Cat sizes the H55Ds for its skid steer and multi-terrain loader line plus the 302.5, 303.5 and 303 CR mini excavators. Recommended carrier operating weight is about 2,500-4,500 kg (5,500-9,900 lb); Cat parts/configurator data shows a wider compatible window up to roughly 6,000 kg (13,230 lb) for some carrier setups, so treat the top end as configuration-dependent and confirm against the specific carrier's hammer chart.

Hydraulic flow and pressure

Cat hammer configurator data lists an acceptable oil flow of about 40-85 L/min (11-22 gpm) with a maximum operating pressure near 16,500-17,000 kPa (2,390-2,465 psi). Some third-party listings show a lower minimum flow, so confirm the exact auxiliary-flow setting against the host machine's own hammer/auxiliary hydraulic circuit before hookup.

Guarding and noise control

The Ds designation is Cat's silenced variant: the power cell is fully enclosed and isolation-mounted on urethane/nylon buffers instead of being rigidly clamped between metal side plates, which cuts jobsite noise and reduces vibration feedback into the carrier compared with a non-silenced hammer of the same size.

All H55DS assemblies by section

Every catalogued assembly group for the Caterpillar H55DS. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Hydraulic System

249-1142 Chart-Connecting Lines

18***22	Seal; (33.7mm Od)	1
23***72	Seal	1
24***42	Chart-Connecting Lines	1
25***37	Ring-Retaining	2

See all parts with full part numbers in Heavy Parts AI →

263-4866 Kit-Seal

15***94	Coupler As-Quick Disconnect; (Female)(Quick Disconnect)	1
15***95	Fitting As; (Quick Disconnect, Male)	1
26***66	Kit-Seal	1
26***72	Hose As	2

See all parts with full part numbers in Heavy Parts AI →

245-3749 Kit-Seal

18***22	Seal; (33.7mm Od)	1
23***72	Seal	1
24***49	Kit-Seal	1
27***57	Seal-Wiper	1

See all parts with full part numbers in Heavy Parts AI →

245-3748 Kit-Seal

18***22	Seal; (33.7mm Od)	1
23***72	Seal	1
24***48	Kit-Seal	1
26***01	Retaining Ring	2

See all parts with full part numbers in Heavy Parts AI →

274-1728 Kit-Seal

15***94	Coupler As-Quick Disconnect; (Female)(Quick Disconnect)	1
15***95	Fitting As; (Quick Disconnect, Male)	1
27***81	Hose As	2
27***28	Kit-Seal	1

See all parts with full part numbers in Heavy Parts AI →

290-3181 Lines Gp-Connecting

15***94	Coupler As-Quick Disconnect; (Female)(Quick Disconnect)	1
15***95	Fitting As; (Quick Disconnect, Male)	1
29***81	Lines Group-Connecting	1
29***13	Hose As	2

See all parts with full part numbers in Heavy Parts AI →

353-8830 Lines Gp-Connecting

15***79	Film-Instruction; (Grease)(Instructions)	1
22***30	Film-Warning; (Flying Debris, Stay Back, U.S.)	2
22***69	Film-Warning; (Do Not Operate, Read Omm)	1
25***16	Film-Identification; (Cat, H65d S)	2

See all parts with full part numbers in Heavy Parts AI →

270-8681 Lines Gp-Connecting

15***94	Coupler As-Quick Disconnect; (Female)(Quick Disconnect)	1
15***95	Fitting As; (Quick Disconnect, Male)	1
27***81	Lines Group-Connecting	1
27***98	Hose As	2

See all parts with full part numbers in Heavy Parts AI →

353-8832 Lines Gp-Connecting

15***79	Film-Instruction; (Grease)(Instructions)	1
22***30	Film-Warning; (Flying Debris, Stay Back, U.S.)	2
22***69	Film-Warning; (Do Not Operate, Read Omm)	1
24***05	Film-Identification; (Cat, H55d S)	2

See all parts with full part numbers in Heavy Parts AI →

329-7275 Lines Gp-Connecting

15***94	Coupler As-Quick Disconnect; (Female)(Quick Disconnect)	1
15***95	Fitting As; (Quick Disconnect, Male)	1
2M***80	Seal--To Connector Pump Outlet	2
32***75	Lines Group-Connecting	1

See all parts with full part numbers in Heavy Parts AI →

290-5679 Lines Gp-Connecting

10***01	Fitting; (Quick Disconnect, Female)	1
10***06	Fitting; (Quick Disconnect, Male)	1
14***39	Connector As.	2
29***79	Lines Group-Connecting	1

See all parts with full part numbers in Heavy Parts AI →

269-7271 Lines Gp-Connecting

15***94	Coupler As-Quick Disconnect; (Female)(Quick Disconnect)	1
15***95	Fitting As; (Quick Disconnect, Male)	1
26***71	Lines Group-Connecting	1
27***99	Hose As	2

See all parts with full part numbers in Heavy Parts AI →

292-0231 Lines Gp-Connecting

14***39	Connector As.	2
29***31	Lines Group-Connecting	1
31***74	Hose As	2
3D***24	O-Ring - For Oil Drain & Level Plug (Items 3 & 7)	2

See all parts with full part numbers in Heavy Parts AI →

270-8682 Lines Gp-Connecting

15***96	Fitting As; (Quick Disconnect, Male)(Quick Disconnect)	1
15***97	Fitting As; (Quick Disconnect, Female)	1
16***11	Clamp	2
27***82	Lines Group-Connecting	1

See all parts with full part numbers in Heavy Parts AI →

330-5359 Lines Gp-Connecting

15***94	Coupler As-Quick Disconnect; (Female)(Quick Disconnect)	1
15***95	Fitting As; (Quick Disconnect, Male)	1
2M***80	Seal--To Connector Pump Outlet	2
30***85	Hose As	2

See all parts with full part numbers in Heavy Parts AI →

330-5361 Lines Gp-Connecting

31***51	Hose As	2
33***61	Lines Group-Connecting	1
3D***24	O-Ring - For Oil Drain & Level Plug (Items 3 & 7)	2
5K***90	Seal-To Hydraulic Cooler Inlet Port	2

See all parts with full part numbers in Heavy Parts AI →

313-6573 Lines Gp-Connecting

15***94	Coupler As-Quick Disconnect; (Female)(Quick Disconnect)	1
15***95	Fitting As; (Quick Disconnect, Male)	1
2M***80	Seal--To Connector Pump Outlet	2
31***73	Lines Group-Connecting	1

See all parts with full part numbers in Heavy Parts AI →

270-8680 Lines Gp-Connecting

15***94	Coupler As-Quick Disconnect; (Female)(Quick Disconnect)	1
15***95	Fitting As; (Quick Disconnect, Male)	1
27***80	Lines Group-Connecting	1
27***26	Hose As	2

See all parts with full part numbers in Heavy Parts AI →

313-4791 Lines Gp-Connecting

15***94	Coupler As-Quick Disconnect; (Female)(Quick Disconnect)	1
15***95	Fitting As; (Quick Disconnect, Male)	1
2M***80	Seal--To Connector Pump Outlet	2
31***91	Lines Group-Connecting	1

See all parts with full part numbers in Heavy Parts AI →

270-8683 Lines Gp-Connecting

15***96	Fitting As; (Quick Disconnect, Male)(Quick Disconnect)	1
15***97	Fitting As; (Quick Disconnect, Female)	1
27***83	Lines Group-Connecting	1
29***78	Hose As	2

See all parts with full part numbers in Heavy Parts AI →

302-4784 Lines Gp-Hydraulic

15***79	Film-Instruction; (Grease)(Instructions)	1
22***30	Film-Warning; (Flying Debris, Stay Back, U.S.)	2
22***81	Film-Warning; -Universal	1
26***52	Film-Identification; (Cat, H35d S)	2

See all parts with full part numbers in Heavy Parts AI →

317-0993 Lines Gp-Hydraulic

15***79	Film-Instruction; (Grease)(Instructions)	1
22***81	Film-Warning; -Universal	1
27***78	Film-Warning; (Flying Debris, Read Omm)	1
27***37	Film-Identification; (Cat H45d S)	2

See all parts with full part numbers in Heavy Parts AI →

Service Equipment And Supplies

245-1503 Film Gp

24***03

Film Group

See all parts with full part numbers in Heavy Parts AI →

245-7422 Film Gp

24***22

Film Group

See all parts with full part numbers in Heavy Parts AI →

254-7643 Film Gp

25***43

Film Group

See all parts with full part numbers in Heavy Parts AI →

274-1627 Film Gp

Work Tool Arrangement

274-1620 Hammer Ar-Hydraulic

27***20	Hammer Ar-Hydraulic	1
27***22	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

311-4904 Hammer Ar-Hydraulic

12***12	Tool Group; (For European Use Only)	1
31***02	Hammer Ar-Hydraulic	1
31***04	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

254-7639 Hammer Ar-Hydraulic

25***39	Hammer Ar-Hydraulic	1
25***42	Hammer Group-Hydraulic	1
25***43	Film Group	1
25***51	Housing Group-Hammer	1

See all parts with full part numbers in Heavy Parts AI →

313-3992 Hammer Ar-Hydraulic

30***93	Hammer Ar-Hydraulic	1
31***92	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

313-3993 Hammer Ar-Hydraulic

12***12	Tool Group; (For European Use Only)	1
31***91	Hammer Ar-Hydraulic	1
31***93	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

315-6121 Hammer Ar-Hydraulic

24***96	Housing Group-Hammer	1
24***22	Film Group	1
30***95	Hammer Group-Hydraulic	1
31***21	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

311-4901 Hammer Ar-Hydraulic

24***01	Housing Group-Hammer	1
24***03	Film Group	1
31***01	Hammer Ar-Hydraulic	1
31***06	Hammer Group-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

249-3161 Hammer Ar-Hydraulic

24***00	Hammer Ar-Hydraulic	1
24***61	Hammer Ar-Hydraulic	1
31***01	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

274-1622 Hammer Ar-Hydraulic

27***22	Hammer Ar-Hydraulic	1
27***23	Housing Group-Hammer	1
27***26	Hammer Group-Hydraulic	1
27***27	Film Group	1

See all parts with full part numbers in Heavy Parts AI →

290-3740 Hammer Ar-Hydraulic

25***39	Hammer Ar-Hydraulic	1
26***29	Tool-Chisel	1
26***30	Tool-Moil Point	1
29***40	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

312-3266 Hammer Ar-Hydraulic

30***81	Hammer Ar-Hydraulic	1
31***66	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

245-1500 Hammer Ar-Hydraulic

24***00	Hammer Ar-Hydraulic	1
24***01	Housing Group-Hammer	1
24***02	Hammer Group-Hydraulic	1
24***03	Film Group	1

See all parts with full part numbers in Heavy Parts AI →

254-7636 Hammer Ar-Hydraulic

12***12	Tool Group; (For European Use Only)	1
25***36	Hammer Ar-Hydraulic	1
29***40	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

311-4902 Hammer Ar-Hydraulic

25***55	Tool-Chisel	1
25***56	Tool-Moil Point	1
30***81	Hammer Ar-Hydraulic	1
31***02	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

297-9362 Hammer Ar-Hydraulic

12***12	Tool Group; (For European Use Only)	1
29***62	Hammer Ar-Hydraulic	1
29***72	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

242-5249 Hammer Ar-Hydraulic

23***79	Hammer Group-Hydraulic	1
24***96	Housing Group-Hammer	1
24***49	Hammer Ar-Hydraulic	1
24***22	Film Group	1

See all parts with full part numbers in Heavy Parts AI →

307-8193 Hammer Ar-Hydraulic

24***22	Film Group	1
30***93	Hammer Ar-Hydraulic	1
30***95	Hammer Group-Hydraulic	1
30***96	Housing Group-Hammer	1

See all parts with full part numbers in Heavy Parts AI →

274-7384 Hammer Ar-Hydraulic

27***84	Hammer Ar-Hydraulic	1
31***21	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

273-0198 Hammer Ar-Hydraulic

12***12	Tool Group; (For European Use Only)	1
27***98	Hammer Ar-Hydraulic	1
27***84	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

275-5863 Hammer Ar-Hydraulic

12***12	Tool Group; (For European Use Only)	1
27***63	Hammer Ar-Hydraulic	1
27***64	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

275-5864 Hammer Ar-Hydraulic

23***82	Tool-Moil Point	1
24***00	Hammer Ar-Hydraulic	1
24***65	Tool-Chisel	1
27***64	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

304-3075 Hammer Ar-Hydraulic

25***39	Hammer Ar-Hydraulic	1
30***75	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

249-0023 Hammer Ar-Hydraulic

24***49	Hammer Ar-Hydraulic	1
24***23	Hammer Ar-Hydraulic	1
31***21	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

307-8181 Hammer Ar-Hydraulic

24***03	Film Group	1
28***64	Housing Group-Hammer	1
30***81	Hammer Ar-Hydraulic	1
30***82	Hammer Group-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

313-3991 Hammer Ar-Hydraulic

23***82	Tool-Moil Point	1
24***65	Tool-Chisel	1
30***93	Hammer Ar-Hydraulic	1
31***91	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

297-9372 Hammer Ar-Hydraulic

27***22	Hammer Ar-Hydraulic	1
27***44	Tool-Chisel	1
27***45	Tool-Moil Point	1
29***72	Hammer Ar-Hydraulic	1

See all parts with full part numbers in Heavy Parts AI →

Work Tools

288-9895 Bracket Gp-Mounting

28***95	Bracket Group-Mounting	1
29***24	Bracket As	1
8T***23	Washer-Plated; (22x35x3.5-mm Thk)	8
8T***31	Nut; (M20x2.5-Thd)	4

See all parts with full part numbers in Heavy Parts AI →

305-4984 Bracket Gp-Mounting

30***84	Bracket Group-Mounting	1
30***42	Bracket As	1
7X***64	Bolt; (M20x2.5x90-mm)	8
8T***23	Washer-Plated; (22x35x3.5-mm Thk)	16

See all parts with full part numbers in Heavy Parts AI →

179-9855 Bracket Gp-Mounting

17***55	Bracket Group-Mounting	1
17***68	Bracket As	1
8T***31	Nut; (M20x2.5-Thd)	8
8T***87	Bolt; (M20x2.5x80-mm)	8

See all parts with full part numbers in Heavy Parts AI →

226-2797 Bracket Gp-Mounting

22***97	Bracket Group-Mounting	1
22***96	Bracket As	1
8T***23	Washer-Plated; (22x35x3.5-mm Thk)	16
8T***31	Nut; (M20x2.5-Thd)	8

See all parts with full part numbers in Heavy Parts AI →

269-7807 Bracket Gp-Mounting

16***20	Pin	4
26***61	Bracket As	1
26***07	Bracket Group-Mounting	1
26***11	Pin	2

See all parts with full part numbers in Heavy Parts AI →

308-9132 Bracket Gp-Mounting

23***82	Tool-Moil Point	1
24***65	Tool-Chisel	1
24***82	Tool-Compacting Plate	1
24***93	Tool-Spade; (Parallel)	1

See all parts with full part numbers in Heavy Parts AI →

304-9772 Bracket Gp-Mounting

16***20	Pin	4
29***62	Set Of Conn Rod Bearing U/S,0.254, Red; -0,127 - Red, Pin, Set Of Conn Rod Bearing U/S,0.254, Red; -0,127 - Green Black	2
30***72	Bracket Group-Mounting	1
30***09	Bracket As	1

See all parts with full part numbers in Heavy Parts AI →

308-7541 Bracket Gp-Mounting

15***68	Bracket Group-Mounting	1
17***55	Bracket Group-Mounting	1
17***58	Bracket Group-Mounting	1
22***97	Bracket Group-Mounting	1

See all parts with full part numbers in Heavy Parts AI →

290-0333 Bracket Gp-Mounting

13***55	Setscrew; (M4x0.7x8-mm)	2
29***33	Bracket Group-Mounting	1
29***53	Bracket As	1
8T***23	Washer-Plated; (22x35x3.5-mm Thk)	8

See all parts with full part numbers in Heavy Parts AI →

300-5047 Bracket Gp-Mounting

30***47	Bracket Group-Mounting	1
30***12	Bracket As	1
7X***54	Bolt; (M16x2x70-mm)	12
7X***64	Bolt; (M20x2.5x90-mm)	8

See all parts with full part numbers in Heavy Parts AI →

298-6360 Bracket Gp-Mounting

29***60	Bracket Group-Mounting	1
30***10	Bracket Group-Mounting	1

See all parts with full part numbers in Heavy Parts AI →

259-1759 Bracket Gp-Mounting

18***20	Locknut; (M20x2.5-Thd)	4
24***57	Bracket As	1
25***59	Bracket Group-Mounting	1
8T***23	Washer-Plated; (22x35x3.5-mm Thk)	8

See all parts with full part numbers in Heavy Parts AI →

305-0511 Bracket Gp-Mounting

13***55	Setscrew; (M4x0.7x8-mm)	2
30***11	Bracket Group-Mounting	1
30***85	Bracket As	1
7X***54	Bolt; (M16x2x70-mm)	12

See all parts with full part numbers in Heavy Parts AI →

280-9827 Bracket Gp-Mounting

28***27	Bracket Group-Mounting	1
29***60	Bracket Group-Mounting	1

See all parts with full part numbers in Heavy Parts AI →

290-7023 Bracket Gp-Mounting

16***20	Pin	4
28***93	Bracket As	1
29***23	Bracket Group-Mounting	1
29***62	Set Of Conn Rod Bearing U/S,0.254, Red; -0,127 - Red, Pin, Set Of Conn Rod Bearing U/S,0.254, Red; -0,127 - Green Black	2

See all parts with full part numbers in Heavy Parts AI →

292-0852 Bracket Gp-Mounting

13***55	Setscrew; (M4x0.7x8-mm)	2
29***52	Bracket Group-Mounting	1
30***48	Bracket As	1
7X***54	Bolt; (M16x2x70-mm)	12

See all parts with full part numbers in Heavy Parts AI →

305-1910 Bracket Gp-Mounting

13***55	Setscrew; (M4x0.7x8-mm)	2
30***10	Bracket Group-Mounting	1
30***42	Bracket As	1
7X***64	Bolt; (M20x2.5x90-mm)	8

See all parts with full part numbers in Heavy Parts AI →

280-9885 Bracket Gp-Mounting

28***85	Bracket Group-Mounting	1
29***34	Bracket As	1
29***18	Rivet	4
8T***23	Washer-Plated; (22x35x3.5-mm Thk)	8

See all parts with full part numbers in Heavy Parts AI →

155-4468 Bracket Gp-Mounting

15***68	Bracket Group-Mounting	1
15***77	Bracket As	1
8T***31	Nut; (M20x2.5-Thd)	4
8T***87	Bolt; (M20x2.5x80-mm)	4

See all parts with full part numbers in Heavy Parts AI →

179-9858 Bracket Gp-Mounting

13***55	Setscrew; (M4x0.7x8-mm)	2
17***58	Bracket Group-Mounting	1
17***71	Bracket As	1
7X***54	Bolt; (M16x2x70-mm)	12

See all parts with full part numbers in Heavy Parts AI →

3q-7608 Bracket Gp-Mounting

16***56	Bracket As	1
3Q***08	Bracket Group-Mounting	1
7X***54	Bolt; (M16x2x70-mm)	12
7X***64	Bolt; (M20x2.5x90-mm)	8

See all parts with full part numbers in Heavy Parts AI →

276-8738 Bracket Gp-Mounting

16***20	Pin	4
27***46	Pin	2
27***38	Bracket Group-Mounting	1
27***39	Bracket As	1

See all parts with full part numbers in Heavy Parts AI →

7q-8466 Bracket Gp-Mounting

16***58	Bracket As	1
7Q***66	Bracket Group-Mounting	1
7X***54	Bolt; (M16x2x70-mm)	12
8T***23	Washer-Plated; (22x35x3.5-mm Thk)	16

See all parts with full part numbers in Heavy Parts AI →

249-1113 Chart-Hammer Mounting

24***13	Chart-Hammer Mounting	1
25***55	Tool-Chisel	1
25***56	Tool-Moil Point	1
25***59	Tool-Compacting Plate	1

See all parts with full part numbers in Heavy Parts AI →

246-0264 Chart-Hammer Tool

24***64	Chart-Hammer Tool	1
26***29	Tool-Chisel	1
26***30	Tool-Moil Point	1
26***31	Tool-Compacting Plate	1

See all parts with full part numbers in Heavy Parts AI →

254-1431 Chart-Hammer Tool

25***31	Chart-Hammer Tool	1
27***44	Tool-Chisel	1
27***45	Tool-Moil Point	1
27***46	Tool-Compacting Plate	1

See all parts with full part numbers in Heavy Parts AI →

263-4728 Chart-Hammer Tool

14***95	Plug As	4
14***09	Plug As-Sto	4
15***52	Diaphragm; (High Pressure)	1
16***77	Plug As	1

See all parts with full part numbers in Heavy Parts AI →

274-3843 Chart-Hammer Tool

14***95	Plug As	2
14***09	Plug As-Sto	4
15***52	Diaphragm; (High Pressure)	1
16***77	Plug As	1

See all parts with full part numbers in Heavy Parts AI →

307-8195 Hammer Gp-Hydraulic

12***66	Pin	2
24***02	Housing; (Lh)	1
24***03	Housing; (Rh)	1
24***03	Damper; (Rh)	1

See all parts with full part numbers in Heavy Parts AI →

245-1502 Hammer Gp-Hydraulic

14***95	Plug As	3
16***77	Plug As	1
18***22	Seal; (33.7mm Od)	1
20***83	Plug As	1

See all parts with full part numbers in Heavy Parts AI →

307-8182 Hammer Gp-Hydraulic

17***93	Bolt-Socket Head; (M20x2.5x80-mm)	4
20***83	Plug As	1
23***72	Seal	1
23***86	Pin-Split	2

See all parts with full part numbers in Heavy Parts AI →

238-1879 Hammer Gp-Hydraulic

14***95	Plug As	3
18***22	Seal; (33.7mm Od)	1
20***83	Plug As	1
23***72	Seal	1

See all parts with full part numbers in Heavy Parts AI →

254-7642 Hammer Gp-Hydraulic

17***93	Bolt-Socket Head; (M20x2.5x80-mm)	4
20***83	Plug As	1
23***72	Seal	1
23***86	Pin-Split	2

See all parts with full part numbers in Heavy Parts AI →

274-1626 Hammer Gp-Hydraulic

14***09	Plug As-Sto	4
17***93	Bolt-Socket Head; (M20x2.5x80-mm)	4
18***22	Seal; (33.7mm Od)	1
20***83	Plug As	1

See all parts with full part numbers in Heavy Parts AI →

311-4906 Hammer Gp-Hydraulic

12***66	Pin	2
17***93	Bolt-Socket Head; (M20x2.5x80-mm)	6
24***04	Housing; (Lh)	1
24***05	Housing; (Rh)	1

See all parts with full part numbers in Heavy Parts AI →

242-1996 Housing Gp-Hammer

12***66	Pin	2
21***10	Bolt-Socket Head; (M16x2x80-mm)	4
24***96	Housing Group-Hammer	1
25***42	Plug	1

See all parts with full part numbers in Heavy Parts AI →

274-1623 Housing Gp-Hammer

12***66	Pin	2
24***03	Damper; (Rh)	1
24***04	Damper; (Lh)	1
24***05	Pad; (Upper)	2

See all parts with full part numbers in Heavy Parts AI →

307-8196 Housing Gp-Hammer

10***96	Pin-Keeper	4
24***61	Pin	2
25***45	Bushing	2
25***46	Bushing	2

See all parts with full part numbers in Heavy Parts AI →

254-7651 Housing Gp-Hammer

12***66	Pin	2
17***93	Bolt-Socket Head; (M20x2.5x80-mm)	6
24***06	Damper; (Lh)	1
24***07	Damper; (Rh)	1

See all parts with full part numbers in Heavy Parts AI →

245-1501 Housing Gp-Hammer

12***66	Pin	2
22***90	Bolt-Socket Head; (M16x2x90-mm)	4
24***06	Plug As	1
24***01	Housing Group-Hammer	1

See all parts with full part numbers in Heavy Parts AI →

281-3064 Housing Gp-Hammer

10***96	Pin-Keeper	4
24***62	Pin	2
25***43	Bushing	2
25***44	Bushing	2

See all parts with full part numbers in Heavy Parts AI →

252-1211 Mounting Gp-Hammer

10***96	Pin-Keeper	4
24***61	Pin	2
25***70	Bushing	2
25***11	Mounting Group-Hammer	1

See all parts with full part numbers in Heavy Parts AI →

316-0412 Mounting Gp-Hammer

18***22	Seal; (33.7mm Od)	1
23***72	Seal	1
23***73	Seal	1
24***01	Retaining Ring	2

See all parts with full part numbers in Heavy Parts AI →

316-0411 Mounting Gp-Hammer

26***71	Lines Group-Connecting	1
27***80	Lines Group-Connecting	1
27***81	Lines Group-Connecting	1
27***82	Lines Group-Connecting	1

See all parts with full part numbers in Heavy Parts AI →

249-1145 Mounting Gp-Hammer

10***96	Pin-Keeper	4
24***61	Pin	2
24***45	Mounting Group-Hammer	1
25***45	Bushing	2

See all parts with full part numbers in Heavy Parts AI →

283-1502 Mounting Gp-Hammer

10***96	Pin-Keeper	4
28***02	Mounting Group-Hammer	1
28***09	Bushing	2
28***11	Pin	2

See all parts with full part numbers in Heavy Parts AI →

250-9878 Mounting Gp-Hammer

10***96	Pin-Keeper	4
25***78	Mounting Group-Hammer	1
28***09	Bushing	2
28***10	Bushing	2

See all parts with full part numbers in Heavy Parts AI →

249-1144 Mounting Gp-Hammer

10***96	Pin-Keeper	4
24***61	Pin	2
24***44	Mounting Group-Hammer	1
25***70	Bushing	2

See all parts with full part numbers in Heavy Parts AI →

H55DS serial number reference

The PIN/serial plate on this hammer is a metal tag riveted or bolted to the hammer housing, usually near the top mounting bracket or back head. Read the first three characters as the letter prefix, followed by the sequence number, e.g. BWM00123 or FTF00456. The H55DS shares its parts book with three other hammer sizes built on the same platform (H35DS, H45DS, H65DS), and each size carries its own distinct prefix - confirm the full stamped PIN against a parts lookup or your dealer rather than guessing size from a partial read.

Prefix	Identifies	Notes
BWM	Original production series (S/N BWM1-UP / BWM00001-UP)	Base prefix for the H55DS in the parts book shared with the H35DS, H45DS, and H65DS. A separate European-market-only build exists within this range for some hydraulic component groups - check the group callout for your unit rather than assuming one config across the whole range.
FTF	Later running-change series (S/N FTF1-UP), follows BWM	Later production block on the H55DS, picking up after a running change. Some component groups pair FTF1-UP with BWM2000-UP as concurrent revision ranges for the same part group. This is a later series of the same model, not a different hammer size.

Frequently asked questions

What carrier weight class and working weight does the H55DS need?

The H55DS is built for carriers in roughly the 2.5-4.5 t (5,500-9,900 lb) class in pin-on form; some flat-top setups are documented up to about 6.0 t (13,200 lb), so treat the top end as configuration-dependent and confirm against your carrier's own hammer chart. Working weight itself is 199 kg (439 lb) pin-on or 250 kg (551 lb) flat-top, including the standard tool and mounting group. It's sized for skid-steer and multi-terrain loaders plus the 302.5C, 303C CR, and 303.5C CR mini excavators.

What hydraulic flow and pressure does the H55DS require?

It needs about 40-85 L/min (10.6-22.5 gpm) of auxiliary flow at a maximum operating pressure near 170 bar (16,500-17,000 kPa, about 2,390-2,465 psi); some configurations or carrier setups are documented down to roughly 30 L/min, so match the exact setting to your own carrier's auxiliary/breaker circuit rather than the general range alone. Too little flow gives weak, slow-cycling hits; too much flow or pressure risks blown seals, hoses, or the accumulator diaphragm and speeds up bushing wear.

How does the H55DS compare to its siblings, and what replaced it?

The H55DS sits in Cat's D-box generation of small silenced hammers alongside the H25D, H35D S, H45D S, and H65D S, all built on the same platform but each a different size and weight class with its own recommended carrier range; don't carry one size's specs over to another. This exact model runs two documented serial-prefix production blocks, BWM and later FTF; any other prefix on a hammer sharing this parts book belongs to a different sibling size, so always confirm the full stamped serial before ordering parts. This research doesn't document a specific model-for-model successor for the H55DS itself.

What H55DS owners discuss

What hydraulic flow and pressure does the H55DS need, and what happens if the carrier doesn't match?

Rated flow sits around 30-85 L/min (7.9-22 gpm) with a maximum operating pressure near 16 500 kPa (2,393 psi), and the hammer is sized for skid steer/compact track loader and mini excavator carriers in roughly the 2 500-4 500 kg (5,500-9,900 lb) class. Too little flow gives weak, slow-cycling hits that never reach full blow energy. Too much flow or pressure from an oversized carrier risks blown seals, hoses, or the accumulator diaphragm and speeds up bushing wear. Check the carrier's rated auxiliary circuit output against the hammer's range before pairing them, not just quick-coupler fit.

Why do operators warn so much about blank-firing this hammer, and how do you avoid it?

Blank-firing means the tool cycles with nothing loaded against it, either firing into open air or continuing after the material breaks free underneath. With no material to absorb the blow, the piston energy dumps straight into the retainer pin and tool bushing. Community consensus treats this as one of the fastest ways to crack a retainer, batter the bushing bore, and send shock load back through the carrier's boom pins. Keep steady down-pressure so the tool stays loaded, release the trigger the instant the material lets go, and reposition instead of holding the trigger open.

What's the normal tool-bushing wear pattern on the H55DS, and when does it need attention?

The lower (front) bushing takes the side-load from prying and levering and wears first, showing up as tool wobble and play that gets worse the longer it's ignored. Because this generation of hammer runs a simplified internal parts count compared to the model it replaced, the bushing is one of the few routine wear items owners flag for regular checks. Once play exceeds the service limit, the fix is a bushing rotation or replacement; running it loose accelerates tool breakage and can wear the housing bore itself.

How often does this hammer actually need greasing, and does the grease type matter?

A manual grease point typically takes on the order of 10-15 gun strokes, and the community habit for this size class is to grease well more often than once a shift, commonly every 2-3 hours of active hammering, since the tool-to-bushing interface runs dry fast under continuous impact. Use a high-load, impact-rated chisel grease rather than general chassis grease. Skipped or stretched intervals are the most cited cause of premature bushing and tool wear on these hammers.

What are the warning signs that the nitrogen accumulator or diaphragm needs service?

Supply hoses bouncing or hopping noticeably during operation, a falling cycle rate, or the tool hesitating at the top of its stroke all point to a nitrogen pre-charge that has drifted low. If the diaphragm itself has failed, the hammer keeps tapping but loses real breaking force. Cat's service guidance calls for inspecting or replacing the seal set and diaphragm roughly every 600 hours or once a year, whichever comes first. Nitrogen recharge work runs at very high pressure, so have your dealer verify pre-charge and perform any recharge rather than doing it in the field.

The hammer suddenly stops cycling. What should get checked before assuming it's broken?

The most commonly reported cause is something simple: a shutoff valve left closed, a quick coupler not fully seated, or the carrier's auxiliary circuit not switched into breaker mode. Confirm hydraulic fluid level on the carrier and full coupler engagement first. If flow and mode check out and it still won't cycle, the next suspects are a low accumulator charge or a sticking internal valve, at which point have your dealer verify before opening the tool up.

What should you check when buying a used H55DS?

Confirm the serial/model plate actually reads the DS manual-grease variant and matches the size you think you're buying, since specs and service parts vary across the family. Inspect the housing for cracked or stretched fasteners, check the front head and tool holder for cracking or scoring, feel for play in the tool bushing, and look for oil weeping around the accumulator or cylinder seals. Cycle it under real load if you can and listen for hose bounce (low nitrogen charge) or a hollow tap with little bite (failed diaphragm). Ask for maintenance records showing grease frequency and the last reseal or recharge date; an example with heavy duty-cycle hours and no service history is a bigger risk than one with more hours and clean records.

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

Need a specific H55DS part?

Search live OEM part data, check fitment, and cross-reference alternatives with Heavy Parts AI.

Search parts in the app