JCB 802.7 803 804 Mini Crawler Excavator Service Repair Manual

HYDRAPOWER MINI-EXCAVATOR SERVICE MANUAL Publication 9803/3110 802.7 M747001 on 803 M665001 on 803 M666001 on 803 M765001 on 804 M734001 on

Hydraulics 9803/3110 Issue Section E Section E 3* 2 - 1 2 - 1

2 - 2 2 - 2 Hydraulics 9803/3110 2 Issue4* 2 HYDRAULIC CIRCUIT (SCHEMATIC) *803 Machines Component Key P1 Pump Section 1 P2 Pump Section 2 P3 Pump Section 3 P4 Pump Section 4 to M665736 T Tank E Engine 1 Main Relief Valve Test Block 1A Swing/Slew Dozer Main Relief Valve 1B Digging and Tracking Main Relief Valve 1C Servo Main Relief Valve 1D Pressure Reducing Valve 1E By-pass Filter 1F Non-return Valves 1G Gauge Connection Points 2 Valve Block 2A Auxiliary Relief Valves 2B Auxiliary Spool 2C Track Spool to M665736 2D Boom Boost Spool 2E Dipper Spool 2F Non-return Valves 2G Auxiliary Couplings (Double Acting) 2H Auxiliary Couplings (Single Acting) 3 Valve Block 3A Auxiliary Relief Valves 3B Track Spool 3C Boom Spool 3D Bucket Spool 3E Non-return Valves 3F Restrictor 4 Valve Block to M665736 4A Auxiliary Relief Valves to M665736 4B Slew Spool 4C Swing Spool 4D Dozer Spool 4E Non-return Valves to 665736 5 L.H. Track Motor 5A Counterbalance Valve 6 R.H. Track Motor 6A Counterbalance Valve 7 Slew Motor 7A Brake Valve 8 Rotary Coupling 9 Dipper Ram 10 Boom Ram 11 Bucket Ram 12 Swing Ram 13 Dozer Ram 14 R.H. Servo Hand Controller 14A Boom Control 14B Bucket Control 14C Check Valves (Standard setup) 15 L.H. Servo Hand Controller 15A Swing / Slew Control 15B Dipper Control 16 Dual Solenoid Valve 17 Return Filter 18 Suction Strainer 19 High Speed Selector *20 Accumulator M665143 on 21 Solenoid Lock Valve 22 High Pressure Carry Over (HPCO) M666001 on 23 Servo Pressure Maintenance Valve Block M666001 on 23A Pressure Maintenance Valve M666001 on 24 Oil Cooler M666001 on

2 - 6 2 - 6 Hydraulics 9803/3110 2 Issue4* 2 SERVO CIRCUIT *803 to M665736 Section P4 of the engine driven pump supplies oil to the servo circuit. The flow for servo actuation is very small and is dead-ended at the controls when they are in netural. Excess flow is directed from the pressure side of the pump to the suction side. Oil is fed via a filter 10 and non-return valve 11 into accumulator 1. This stores sufficient pressure to ensure limited operation of the controls in the event of engine or pump failure. High speed track selector 2 and servo cab controls 3 and 4 are fed via solenoid lock valve 5 which is controlled by an isolator switch. When the left hand seat pod is in the 'down' position, the switch is closed, energising solenoid valve 5 which directs oil from line 1a to the controls via line 5b. The servo cab controls direct pressure as required to operate the excavator spools in the main control valves 6 and 7. Solenoid lock valve 5 also supplies pressure to the dual solenoid valve 8 which operates the control valve spool for swing and slew. When the left hand seat pod is raised, the isolator switch opens, de-energising solenoid lock valve 5, connecting ports B to A and blocking port C. Pressure is exhausted to tank T and the servo cab controls are thereby isolated, thus preventing accidental operation of the services. The exhaust from the hand controls is now directed to tank T. SERVO HAND CONTROL CIRCUIT The control lever is mounted on a universal joint to allow actuation of four plungers, each of which is connected, via service ports and pipework, to one end of a spool in the control valve block. Each plunger port contains a plunger with its return spring and a spool. With the lever in neutral, oil from the pumps enters via a central port but is unable to flow any further than the spools. The service ports are connected to the tank via the hollow centre of the spool and through a cross- drilling into the annular passage which connects to a tank port. When the lever has been moved to depress a spool, the cross-drilling is aligned with a pressure gallery, allowing pressure to actuate the relevant spool of the control valve block. Pressure from the opposite end of the main control valve spool is exhausted to tank via a hand control plunger which has remained in netural. When pressure has increased sufficiently to overcome spool spring pressure, pressure builds up in the line, moving the spool upwards so that the cross-drilling moves up into the control housing. This reduces the flow of oil through the port to the relevant control valve, so balancing out the pressure in both this line and the line from the pump. If the control lever is moved slowly, this metering can be used to operate the relevant service gradually. KEY TO SERVO HAND CONTROL PORTS Servo Port Colour Service 3a Yellow 3b No Tag 3c Dark Green TBA 3d Natural 3e Red 3f Dark Blue 4a Dark Green 4b No Tag 4c Purple TBA 4d Natural 4e Dark Blue 4f Orange

Hydraulics 9803/3110 Issue 2 2 2* 2 - 7 2 - 7 2D 2E 2C 5 6 6A 5A 8 13 12 19 2H 2G 3F 11 10 2F 9 2F 2 2A 2A 2A 2A 3D 3C 2B 3 3B 4C 4B 4D 1A 3A 3E 14 14A 14B 14C 15 15A 15B 16 1 1F 1B 1D 23 1G 23A 1C 21 23B H03672 1G 1G 1G 24 17 E P P3 P2 P1 T 18 a b c d g f e h j k g h j k a d b c f e 7 7B 7A 7A 7B 20 5B 6B 22

Hydraulics 9803/3110 Issue 2 2 3* 2 - 8 2 - 8 HYDRAULIC CIRCUIT (SCHEMATIC) *803 M666001 on & M765001 on Component Key P1 Pump Section 1 P2 Pump Section 2 P3 Pump Section 3 T Tank E Engine 1 Main Relief Valve Test Block 1A Swing/Slew Dozer Main Relief Valve 1B Digging and Tracking Main Relief Valve 1C Servo Main Relief Valve 1D Pressure Reducing Valve 1F Non-return Valves 1G Gauge Connection Points 2 Valve Block 2A Auxiliary Relief Valves *2B RH Track Spool *2C LH Track Spool 2D Boom Boost Spool 2E Dipper Spool 2F Non-return Valves 2G Auxiliary Couplings (Double Acting) 2H Auxiliary Couplings (Single Acting) 3 Valve Block 3A Auxiliary Relief Valves 3B Auxiliary Spool 3C Boom Spool 3D Bucket Spool *3E Anti cavitation Valves 3F Restrictor *4B Swing Spool *4C Slew Spool 4D Dozer Spool 5 L.H. Track Motor 5A Counterbalance Valve *5B Two Speed Tracking Valve 6 R.H. Track Motor 6A Counterbalance Valve *6B Two Speed Tracking Valve 7 Slew Motor 7A Brake Valve *7B Crossline Relief Valves 8 Rotary Coupling 9 Dipper Ram 10 Boom Ram 11 Bucket Ram 12 Swing Ram 13 Dozer Ram 14 R.H. Servo Hand Controller 14A Boom Control 14B Bucket Control 14C Check Valves (Standard setup) 15 L.H. Servo Hand Controller 15A Swing / Slew Control 15B Dipper Control *16 Slew/Swing Changeover Valve 17 Return Filter 18 Suction Strainer 19 Track High Speed Selector 20 Accumulator 21 Solenoid Lock Valve 22 High Pressure Carry Over (HPCO) M666001 on 23 Servo Pressure Maintenance Valve Block 23A Pressure Maintenance Valve 24 Oil Cooler Auxiliary Relief Valves Auxiliary relief valves (A.R.V.), are fitted to protect the dipper, boom and the head side only of the dozer ram from damage that might be generated through over- pressure conditions during operation. When the A.R.V.'s are open, excess pressure is vented back to tank T. The service lines to the dozer ram, the track motors and the pilot line from the high speed selector to the track motors are routed through a rotary coupling 8. This device allows the machine upper structure to turn without damaging hoses connected to services mounted on the undercarriage. The remaining service lines connect directly to their relevant devices. Return fluid from services or from the neutral pressure circuit is routed back to tank through an exhaust line and return filter 17. Neutral Circuit Pressure With the engine running, and no services selected oil flow from pumps P1, P2, and P3 circulates through the valve blocks. The valve spools are spring loaded to the centre neutral circuit position, allowing the hydraulic fluid to pass through their open centres and back to tank via an oil cooler 24 and filter 17. The 2.8 Tonne mini-excavator hydraulic circuit is fed from an hydraulic tank T, located to the right of the operator's cab. The system is powered by a three section gear pump P connected to the engine crankshaft . When the engine is running, the pump sections P1, P2 and P3 draw fluid from the tank T. Oil from sections P2 and P3 is routed through a main relief valve test block 1 and into the six spool control valve block 2, a high pressure carry over (H.P.C.O.) hose 22 allows oil to flow from the six spool valve block into the four spool valve block 3. Pump section P1 is routed through a servo pressure maintenance valve block 23 and on into the inlet section of the four spool control valve block, Pump section P1 supplies the control valve sections for: - Dozer ram, 13 - Swing ram, 12 - Slew motor, 7 - Servo hand controllers - High speed track selector 19 The supply line to the high speed track selector and servo hand controllers is via a solenoid lock valve 21. Pump section P2 supplies the control valve sections for: - Right hand track motor, 6 - Boom ram, 10 - Bucket ram, 11 Pump section P3 supplies the control valve sections for: - Left hand track motor, 5 - Dipper ram, 9 - Boom boost, 2D - Auxiliary 2B (supplied by P3 & P1 combined) Main Relief Valves The main relief valve for P1 is located on the inlet side of the four section control valve block and is set to open at 172 bar (2500 lbf/in 2 ). The main relief valve for P2 and P3 is located in the main relief valve test block and has a dual setting of 207 bar (3000lbf/in 2 ) and 175 bar (2550lbf/in 2 ) depending on the hydraulic load on the engine. The valves are designed to protect the pumps against over pressurisation when a selected service is stalled or the ram reaches the end of its travel. The M.R.V opens to vent excess pressure to tank T. Connections to the pump allow the attachment of pressure gauges to permit the setting of the main relief valves.

2 - 9 2 - 9 Hydraulics 9803/3110 2 Issue2* 2 14 14A 14B 14C 15 15A 15B 16 1 1F 1B 1D 23 1G 23A 1C 21 23B H03701 1G 1G 1G 24 17 E P P3 P2 P1 T 18 a b c d g f e h j k 20

2 - 10 2 - 10 Hydraulics 9803/3110 2 Issue3* 2 SERVO CIRCUIT *803 M666001 on Description Flow from pump section P1 enters the servo pressure maintenance valve 23. This immediately pressurises the pump, which on reaching a preset value will open valve 23A, allowing full pump flow to supply the neutral circuit of the slew, swing and dozer spools. Pressure at the pump, will be held by value 23A to the required servo operating pressure. This maintained pressure is sensed via. restrictor 23B to the servo isolator solenoid 21, retained until the solenoid is energised which pushes the spool across against its return spring allowing the pressure to cross the spool and feed the hand controllers 14 and 15. Plungers 14A, 14B, 15A and 15B in the hand controllers meter this pressure to progressively select the required excavator spool as the machine is operated. When either slew, swing or dozer service is selected pump P1 will be pressurised to the demands of that circuit. Because this system pressure is likely to be much higher than the requirements of the servo, it is necessary to install a servo protection M.R.V. 23E, to limit the pressure transmitted to the hand controllers 14 and 15. This M.R.V. senses the pressure via. restrictor 23B, opens and remains open whilst pump P1 is pressurised by the excavator circuit, to vent away excess pressure to tank.

Hydraulics 9803/3110 Issue 2 2 2* 2 - 11 2 - 1 2D 2E 2C 5 6 6A 5A 8 13 12 19 2H 2G 3F 11 10 2F 9 2F 2 2A 2A 2A 2A 3D 3C 2B 3 3B 4C 4B 4D 1A 3A 3E 14 14A 14B 14C 15 15A 15B 16 23 1G 23A 1C 21 23B H05101 1G 1G 1G 24 17 E P P3 P2 P1 T 18 a b c d g f e h j k g h j k a d b c f e 5B 6B 22 1B 1B 20 7B 7A 7C 7C 7A

Hydraulics 9803/3110 Issue 2 2 2* 2 - 12 2 - 12 HYDRAULIC CIRCUIT (SCHEMATIC) 804 machines Component Key P1 Pump Section 1 P2 Pump Section 2 P3 Pump Section 3 T Tank E Engine 1A Swing/Slew/Dozer Main Relief Valve *1B Excavator/Track M.R.V. 1C Servo Main Relief Valve 1G Gauge Connection Point 2 Valve Block 2A Auxiliary Relief Valve *2B RH Track Spool *2C LH Track Spool 2D Boom Boost Spool 2E Dipper Spool 2F Non-return Valve 2G Auxiliary Couplings (Double Acting) 2H Auxiliary Couplings (Single Acting) 3 Valve Block 3A Auxiliary Relief Valve *3B Auxiliary Spool 3C Boom Spool 3D Bucket Spool *3E Anti-cavitation Valve 3F Restrictor *4B Swing Spool *4C Slew Spool 4D Dozer Spool 5 L.H. Track Motor 5A Counterbalance Valve *5B Two Speed Tracking Valve 6 R.H. Track Motor 6A Counterbalance Valve *6B Two Speed Tracking Valve 7 Slew Motor 7A Brake Valve 8 Rotary Coupling 9 Dipper Ram 10 Boom Ram 11 Bucket Ram 12 Swing Ram 13 Dozer Ram 14 R.H. Servo Hand Controller 14A Boom Control 14B Bucket Control 14C Check Valves (Standard setup) 15 L.H. Servo Hand Controller 15A Swing / Slew Control 15B Dipper Control *16 Dual Solenoid Valve Slew/Swing Changeover Valve 17 Return Filter 18 Suction Strainer 19 High Speed Selector 20 Accumulator 21 Solenoid Lock Valve 23 Servo Pressure Maintenance Valve Block 23A Pressure Maintenance Valve 23B Restrictor 24 Oil Cooler to vent excess pressure to tank T. Connections to the pump outlet ports allow the attachment of pressure gauges to permit the setting of the main relief valves. Auxiliary Relief Valves Auxiliary relief valves (A.R.V.), are fitted to protect the dipper, boom and the head side only of the dozer ram from damage that might be generated through over- pressure conditions during operation. The A.R.V.'s are set to operate at the following pressures: - Auxiliary service A.R.V.'s - 172 bar (2500 lbf/in 2 ) - Dipper ram A.R.V.'s - 248 bar (3600 lbf/in2) - Boom ram A.R.V.'s - 248 bar (3600 lbf/in 2 ) - Dozer ram A.R.V.'s - 200 bar (2900 lbf/in 2 ) When the A.R.V.'s are open, excess pressure is vented back to tank T. The service lines to the dozer ram, the track motors and the pilot line from the high speed selector to the track motors are routed through a rotary coupling 8. This device allows the machine upper structure to turn without damaging hoses connected to services mounted on the undercarriage. The remaining service lines connect directly to their relevant devices. Return fluid from services or from the neutral circuit is routed back to tank through an exhaust line, cooler and return filter 17. NEUTRAL PRESSURE CIRCUIT With the engine running, and no services selected oil flow from pumps P1, P2, and P3 circulates through the valve blocks. The valve spools are spring loaded to the centre neutral position allowing the hydraulic fluid to pass through their open centres and back to tank via an oil cooler 24 and filter 17. *The 3.4 Tonne mini-excavator hydraulic circuit is fed from an hydraulic tank T, located to the right of the operator's cab. The system is powered by a single piston pump P connected to the engine crankshaft. The supply from the pump is divided into two equal flows P1 & P2. Pump P3 is a gear pump attached to the back of the piston pump and driven by a common shaft. When the engine is running, the pump sections P1/ P2 and P3 draw fluid from the tank T. Oil from sections P2 and P3 is routed through the centre inlet section of the six section control valve block 1, a high pressure carry over (H.P.C.O.) hose 22 allows oil to flow from the six section valve block into the four section valve block 3 to supply the auxiliary circuit, breaker /auger etc., along with flow from gear pump P3. Pump section P3 is routed through a servo pressure maintenance valve block 23 and on into the inlet section of the four spool control valve block. Pump section P1 supplies the control valve sections for: - Right hand track motor, 6 - Boom ram, 10 - Bucket ram, 11 Pump section P2 supplies the control valve sections for: - Left hand track motor, 5 - Dipper ram, 9 - Boom boost, 2D - Auxiliary 2B (supplied by P2 & P3 combined) Pump section P3 supplies the control valve sections for: - Dozer ram, 13 - Swing ram, 12 - Slew motor, 7 - Servo hand controllers - High speed track selector 19 The supply line to the high speed track selector and servo hand controllers is via a solenoid lock valve 21. Main Relief Valves The main relief valve for P1 is located in the front of the centre inlet section of the six spool control valve block. The main relief valve for P2 is located at the rear of the centre inlet section and both are set to open at 207 bar (3000 lbf/in 2 ). P3 is located in the inlet section of the four spool valve block and is set to open at 150 bar (2170 lbf/in 2 ). The valves are designed to protect the pumps against over pressurisation when a selected service is stalled or a ram reaches the end of its travel. The M.R.V opens

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JCB 802.7 803 804 Mini Crawler Excavator Service Repair Manual

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