Part of the JCB Repair Manuals.
Discharging the low and high pressure accumulators opens the disassembly sequence in this 87-page JCB HM012T service manual PDF (OEM ID 9813/5850-01), which covers 14 hydraulic breaker variants from HM012T to HM380T. Power cell teardown runs through the tie rods, cylinder, piston, valve housing and valve spool, and reassembly finishes with tie rod tightening, gas charging and grease charging on models with automatic greasing. A conversion table for N2 charging of the low pressure accumulator sits with the Fault Finding section and the torque settings for BSP hose connections and Code 62 SAE flange couplings. Measure the bottom bush against its 3 mm to 7 mm wear limit, and check tools against limits from 41 mm to 170 mm, depending on model. Your order may be a worn upper bush or retainer pin. Searchable text and bookmarks take you to the Part Numbers chapter, listed by breaker model, so you order the right number the first time.
What's Inside This JCB HM012T to HM380T Manual
| System | Pages | Key Topics |
|---|---|---|
| Introduction | 1-16 | About This Manual, Safety, Service Tools |
| Maintenance | 17-26 | Health and Safety (Safety First, Lubricants), Wearing Parts, Lower Tool Bushing and Tools (Checking for Excessive Wear, Check for and Removal of Burrs) |
| Accumulators Discharge | 27-28 | Low Pressure Accumulators, High Pressure Accumulators, Gas Charging Kit, Discharging Procedure |
| Housing Disassembly | 29-31 | Housing (Boxed), Housing (Side Plate), Removing Hoses, Removing Side Bolts |
| Power Cell Disassembly | 32-38 | Power Cell, Tie Rods, Cylinder, Piston, Valve Housing, Valve Spool |
| Tool Bushes Disassembly | 39-40 | Tool Bushes, Press Method, Cutting Method, Welding Method |
| Assembly Procedures | 41-52 | High Pressure Accumulator, Valve, Piston Seal, Tool Housing Assembly, Cylinder, Tightening Tie Rods |
| Gas Charging and Final Assembly | 53-64 | Angle Method, Torque Method, Low Pressure Accumulator, High Pressure Accumulator, Grease Charging |
| Service | 65-80 | Repair of Parts (Tool for Correction, Inspection), Automatic Lubrication (Installation, Refilling, Adjuster, Operation, Installment of Tool), Fault Finding |
| Specification | 81-84 | Machine Specification, Torque Settings (BSP Hose Connection, Code 62 SAE Flange Coupling) |
| Part Numbers | 85-87 | Breaker Models |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| HM012T to HM380T | ||
| Tool Wear Limits (Y) | 41 mm (1.61 Inch) to 170 mm (6.69 Inch) | p. 21 |
| Upper Bush Wear Limit (D) | 5 mm (0.2 Inch) to 9 mm (0.35 Inch) | p. 21 |
| HM033T to HM380T | ||
| Upper Bush Wear Limit (E) | 8 mm (0.31 Inch) to 22 mm (0.87 Inch) | p. 81 |
| HM012T | ||
| HM012T Operating Weight | 120 kg | p. 81 |
| HM012T Tool Diameter | 45 mm | p. 81 |
| HM012T Low Pressure Accumulator | 10-14 bar | p. 81 |
| HM012T Quantity of Hydraulic Oil | 40 cc | p. 55 |
| HM012T BSP Hose Connection Torque | 50-55 Nm | p. 83 |
| HM380T | ||
| HM380T Operating Weight | 3,800 kg | p. 81 |
| HM380T Low Pressure Accumulator | 14-16 bar | p. 81 |
| HM380T Quantity of Hydraulic Oil | 700 cc | p. 56 |
| HM200T | ||
| HM200T BSP Hose Connection Torque | 190-209 Nm | p. 83 |
JCB HM012T to HM380T Common Problems This Manual Covers
JCB HM012T to HM380T hydraulic breaker does not start or run when the auxiliary circuit is operated
Check the hoses first: P must go to the pump/pressure line and T to the tank/return line, per page 74. Before disconnecting any hose, stop the engine and, with the starter switch ON, operate the auxiliary controls a few times to vent pressure (page 9). Open the auxiliary ball valve with the retainer, put load on the tool, then check the return line and renew the filter. Seized switch spool or piston failure: contact your JCB dealer.
Manual Section: Fault Finding - Breaker does not start or run p. 74Breaker runs slow on the carrier even with hoses connected the correct way
Check the ball valve is open and locked with the retainer, then correct pump mode and pilot pressure valve setting. Check low pressure accumulator pressure against the value for your model on page 81, and the high pressure accumulator for high gas pressure; both force oil over the relief valve. Verify restrictor size, adjuster valve setting and stroke valve following page 74.
Manual Section: Fault Finding - Breaker runs slow p. 74Hydraulic breaker loses breaking power during operation after running normally on the same carrier
Check HP and LP accumulator precharge at the correct temperature and recheck 5 minutes later, following page 75. Carry out a flow and pressure check on the carrier for faulty ARV/MRV, verify machine setting and lock the ball valve open. Take an oil sample if oil is degraded. If HP precharge keeps dropping, discharge the accumulator per page 27 before inspecting it; page 8 warns accumulators stay pressurised with no hydraulic pressure.
Manual Section: Fault Finding - Loss of breaking power p. 75Breaker hydraulic hoses vibrate excessively while the hammer is firing on the carrier
Check HP accumulator precharge, adjust it, and recheck 5 minutes later following page 75. Charge only with nitrogen; page 56 warns any other gas can make the accumulator explode, and nitrogen displacing air can suffocate you. If vibration persists, discharge the HP accumulator per page 27 and inspect it, remembering page 8: it stays pressurised with no hydraulic pressure. HM012T and HM018T have no HP accumulator (page 41).
Manual Section: Fault Finding - Hose vibration p. 75Hydraulic oil leaking from the tool bush at the front of the breaker
Inspect the piston and seal following page 76, and check tool and bush clearance against the wear limits on page 21; debris and angular tool strikes damage the seal. After a service, suspect an incorrectly installed seal first. Check carrier set up and cooling for overheating, pre warm the breaker for low temperature operation, and observe the 15s rule.
Manual Section: Fault Finding - Oil leaking from tool bush p. 76Automatic lubrication cartridge not greasing the tool, with no visible grease mark on the shank
Check the grease mark on the tool: it should equal the tool diameter, so adjust the CONTI LUBE to increase lubrication following page 76. Stop the engine and remove the starter key before servicing the cartridge (page 10). Replace or refill an empty cartridge, inspect it for damage, and verify the seal is fitted, the cartridge is screwed in and its end is open. Check machine set up and cooling if grease melts out.
Manual Section: Fault Finding - Lack of lubrication p. 76Frequently Asked Questions
What are the hydraulic flow and pressure requirements for the JCB HM series breakers?
The hydraulic flow and pressure requirements vary by model. For example, the HM012T requires 12-25 l/m flow and 90-120 bar operating pressure, while the HM380T requires 204-272 l/m flow and 150-190 bar operating pressure. Refer to the Machine Specification table on page 81 for the complete list of requirements for all models. p. 81
What causes a JCB HM breaker to stop striking?
A breaker may stop striking due to several issues, such as the auxiliary ball valve being closed, a seized switch spool, or the breaker being connected backwards. Additionally, if there is no load on the tool, the blank fire protection will prevent operation. Refer to the Fault Finding table on page 74 for a complete list of causes and solutions. p. 74
How do you adjust the impact speed on a JCB HM breaker?
The impact speed is adjusted by changing the oil flow using the adjuster valve. For high speed (low power), turn the adjuster counter-clockwise for 2 cycles. For low speed (high power), turn the adjuster clockwise until fully tightened, then tighten the nut after setting. See page 26 for the detailed procedure. p. 26
What is the torque setting for tightening the tie rod nuts on an HM080T breaker?
For the HM080T model, the tie rod nuts should be tightened to a final torque of 1274 Nm using the Torque Method. Refer to the Tightening Way table on page 54 for the specific steps and torque values for each model. p. 54
How much hydraulic oil is required to fill the low pressure accumulator for an HM080T breaker?
The HM080T model requires 200 cc of hydraulic oil to fill the low pressure accumulator. Refer to the table on page 55 for the specific oil quantities required for all models. p. 55
Is this JCB HM012T manual a PDF I download?
All 87 pages arrive as one searchable PDF at checkout. Read it at the desk, then take the phone out to the machine.
Is this JCB HM012T Service Manual printable?
Yes. Printing works from any reader and any printer, for your own shop use.
