Below is a page-by-page contents list and a summary: how the hammer circuit works on machines of different build years, what flow and pressure a hand-held tool needs, and how to handle quick release couplings correctly. Page numbers follow the manual’s own numbering (A-1, A-35 and so on).
Contents by Page — JCB 3CX / 4CX Attachments
| Pages | What the section covers |
|---|---|
| A-1 – A-4 | Hammer circuit on gear pump machines with extending dipper up to September 2007: circuit, connectors and wiring |
| A-5 – A-8 | Hammer circuit on gear pump machines from September 2007: single and double pump flow |
| A-9 – A-14 | Hammer circuit on variable flow pump machines and on Precision Control joystick machines |
| A-15 – A-19 | Connecting and disconnecting hoses, quick release couplings, return line filter renewal |
| A-20 – A-30 | Hydraulic tool circuit (HTC): operation, electrics on lever and joystick machines, hoses and couplings |
| A-31 – A-36 | HTC flow divider: removal, dismantling, flow and pressure test |
| A-37 onwards | 3 point hitch (214e Landscaper): control valve and rams |
How the Hammer Circuit Works on the JCB 3CX
The circuit layout depends on the build year and the pump type, so make sure you open the right circuit diagram before starting any repair.
- Gear pump machines up to September 2007 (page A-1). The hammer is operated by the auxiliary hydraulics switch in the side console and a foot switch in the cab. Oil is supplied through two lines: F1 from the second pump section via the priority valve and the auxiliary valve, and F2 from the main section, which the hammer solenoid valve blocks off from tank. The manual shut-off valve is set to “closed” for hammer work. The change-over valve isolates the extending dipper at the same time, so the dipper cannot be extended while the hammer is in use.
- Gear pump machines from September 2007 (page A-5). The hammer circuit is completely independent of the extending dipper circuit. A three-position switch selects single or double pump flow. In single flow, hydraulic speed control (HSC) is engaged automatically and the second pump section dumps its oil to tank, so the hammer runs on the main section alone. In double flow the hammer receives the flow from both sections. Return oil passes through the oil cooler, and a small nitrogen-charged accumulator on the return line smooths out pulsations.
- Variable flow pump machines (page A-9). Line F1 comes from the auxiliary section of the excavator valve and F2 from the main circuit. The return line carries a filter and a nitrogen-charged accumulator that protects the filter element from pressure pulses.
On sideshift machines the hammer works only with the carriage hydraclamps applied — the clamp switch must be in the OFF position. The return line filter is renewed as follows (page A-19): vent the pressure, unscrew the old element, smear the seal of the new one with hydraulic oil, screw it on until it makes contact and then a further half turn, and check for leaks. The manual specifies a JCB-supplied filter, otherwise the system may be damaged by contamination. Hammer parts can be found under JCB hydraulic hammer parts, and filters under filters.
Hydraulic Tool Circuit (HTC)
Hand-held hydraulic tools are connected to the HTC through “pressure” and “return” quick release couplings (page A-20). A flow divider supplies the tool with a regulated flow regardless of load and pump output; any excess above 20 l/min goes to other services, such as the loader. An integral relief valve dumps oil to tank if the pressure is exceeded.
| Item | Value |
|---|---|
| Tool category | class C |
| Flow to the tool | 20 l/min |
| Relief valve setting | 138 bar |
| Engine speed for the test | 1500 rev/min |
Flow and pressure must be checked before a tool is connected (page A-35). Fit a pressure gauge, a flow meter and a restrictor between the pressure and return couplings, and open the restrictor fully before starting. At 1500 rev/min with the HTC selected, the flow meter should read 20 l/min; if not, adjust the flow divider screw. Then raise the pressure with the restrictor: the flow should start to drop at 138 bar. After the test, stop the engine, vent the pressure and remove the test equipment.
Quick Release Couplings and Hoses: Good Practice
- Before connecting or disconnecting a hose, vent the residual pressure and make sure the engine cannot be started: a jet of oil under pressure can penetrate the skin. Look for leaks with a piece of cardboard, never with your hand (page A-15).
- A hose must not be twisted or touch hot or moving parts; secure long hoses with clips, but not on a bend — the bend allows for the hose lengthening under pressure (pages A-15, A-16).
- Wipe the faces of flat face couplings before connecting them; connect and disconnect a new coupling 2–3 times to bed in its PTFE seals (page A-17).
- Free a seized coupling with a rubber or hide mallet; tighten adaptors on the hexagon only, never on the plain section.
- Never connect a damaged coupling half — it will destroy the seals and both halves will have to be renewed; never turn the sleeve of a disconnected coupling, and never leave a coupling where it can be crushed.
Quick release couplings and high pressure hoses are listed under hydraulic hoses and quick couplings, valves under hydraulic valves, and buckets and other attachments under attachments. To choose parts, send us the machine model, serial number, year of manufacture and the type of attachment.
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