A mast that creeps under load or a transmission that slips when hot can eat a week of shop time if you work from memory. The Clark CMP50, CMP60, CMP70 service manual PDF answers that with 411 pages of factory data for these diesel forklifts, organized by system from PM schedules to a closing specifications group. Perkins engine work fills over a third of the book and transmission troubleshooting another quarter, while the electrical group carries the circuit diagram. Hydraulic schematics lay out the pump and control valve circuits, backed by steering unit, priority valve, and lift cylinder overhauls. Hold lift cylinder drift to 20 mm per 5 minutes at 50°C oil, and set CMP50 main relief at 200 kg/cm² (2845 psi). Guess wrong and you buy a pump twice. With bookmarks and a text layer, you confirm the fault first, so the part you order is right the first time.
What's Inside This Clark CMP50, CMP60, CMP70 Manual
| System | Pages | Key Topics |
|---|---|---|
| Safe Maintenance | 4-14 | Safety, Lifting, Jacking, And Blocking |
| Periodic Service | 15-29 | Maintenance Schedules, Planned Maintenance, PM Inspection Form |
| Perkins Diesel Engine | 30-182 | General Information, Cylinder Head Assembly |
| Cooling System | 183-186 | Specifications and Description, Troubleshooting |
| Transmission | 187-294 | Disassembly, Reassembly of Transmission, Troubleshooting Guide for the Transmission |
| Electrical | 295-300 | Circuit Diagram, Instrument Pod |
| Drive Axle | 301-313 | Specifications and Description, Drive Axle Overhaul |
| Wheels and Tires | 314-326 | Specifications and Description, Cushion Wheels and Tires, Pneumatic Wheels and Tires |
| Brake System | 327-343 | Service/Inching Brake, Parking Brake |
| Steer System | 344-360 | Specifications and Description, Troubleshooting, Steering System Removals & Installations, Steering System Pressure Check, Steering Unit Overhaul, Priority Valve Overhaul |
| Hydraulic System | 361-378 | Specifications and Description, Troubleshooting, Hydraulic Pump Overhaul, Control Valve Overhaul |
| Uprights | 379-398 | Specifications and Description, Upright Checks and Adjustments, Lift Chain Service, Removals and Replacements, Lift and Tilt Cylinder Overhaul |
| Counterweight | 399-400 | Inspection, Removal and Replacement |
| Specifications | 401-411 | Dimensions and Weight, Performance, Service Specifications by Group, Fluids, Critical Torque, Standard Tightening Torque, Metric Conversion Chart |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Main Pump Displacement | 56.6 cc/rev (3.45 in³/rev) | p. 362 |
| Auxiliary Pump Displacement | 15.2 cc/rev (0.93 in³/rev) | p. 362 |
| Main Valve Relief Pressure | 200 kg/cm² (2845 psi) | p. 362 |
| Main Valve Relief Pressure (CMP 50) | 200 kg/cm² | p. 362 |
| Steer cylinder tie rod nut torque | 5.0 ± 0.5 kg·m (36 ± 4 lbf·ft) | p. 360 |
| Lift cylinder drift | 20 mm/5min | p. 404 |
| Transmission Oil Capacity | 20 L | p. 187 |
| Cooling System Capacity | 17 L | p. 184 |
| Steering Relief Pressure | 140 kgf/cm² | p. 345 |
| Steering Unit Displacement | 200 cc/rev | p. 345 |
Clark CMP50, CMP60, CMP70 Common Problems This Manual Covers
Clark CMP50/CMP60/CMP70 forklift control levers move but hydraulic system gives no lift or tilt operation
Check the circuit on the hydraulic schematic at page 365 before pulling anything, then work the no lift/tilt entries in the Hydraulic System troubleshooting chart. If the pump is the suspect, follow the Hydraulic Pump Overhaul procedure and confirm the main pump is rated 56.6 cc/rev (3.45 in³/rev) as listed on page 362.
Manual Section: Hydraulic System p. 361Hydraulic control valve spool sticking after the lever is released and not returning to neutral
Check the spool sticking entries in the Control Valve troubleshooting chart before swapping parts. If the spool still hangs up, remove the control valve and follow the Control Valve Overhaul procedure in the Hydraulic System section starting on page 361, then use the hydraulic schematic on page 365 to confirm which spool feeds which circuit.
Manual Section: Hydraulic System p. 361With the control valve in neutral, lift or tilt cylinder keeps dropping and the mast drifts
Measure drift with oil at 50°C: lift cylinder drift should not exceed 20 mm in 5 minutes and tilt cylinder drift 15 mm in 5 minutes, per page 404. If either is over spec, work the cylinder dropping in neutral entries in the Control Valve troubleshooting chart, then move to Lift and Tilt Cylinder Overhaul in the Uprights section.
Manual Section: Specifications p. 404Upright raises on the lift cylinders but the load cannot be lifted to maximum height
Check the maximum height entry in the Hydraulic System troubleshooting chart, then run the Upright Checks and Adjustments procedure in the Uprights section starting on page 379 to rule out the upright itself. Inspect the top of each lift cylinder for oil leaks while you are up there, and follow Lift Chain Service if the chains need attention.
Manual Section: Uprights p. 379Steer system feels heavy at the steering wheel and the truck responds with slow steering
Test steering relief pressure using the Steering System Pressure Check procedure and compare the reading to 140 kgf/cm² on page 345. If pressure is on spec, work the heavy and slow steering entries in the Steering System troubleshooting chart, then move to the Priority Valve Overhaul or Steering Unit Overhaul depending on what you find.
Manual Section: Steer System p. 345Perkins diesel engine running too hot with the water pump leaking coolant
Check coolant level with the engine cold; the system holds 17 L per page 184, so a big top-up means coolant is going somewhere. Inspect the water pump for leaks and noise, look for oil in the coolant, then work the running too hot entries in the Cooling System troubleshooting chart.
Manual Section: Cooling System p. 183Frequently Asked Questions
What are the replacement specifications for the hydraulic pump on the Clark CMP50/60/70 forklift?
The main hydraulic pump is a gear-type pump with a rated pressure of 246 kg/cm² (3499 psi) and a displacement of 56.6 cc/rev (3.45 in³/rev). The auxiliary gear pump has a rated pressure of 246 kg/cm² (3500 psi) and a displacement of 15.2 cc/rev (0.93 in³/rev). p. 362
What is the correct torque for the cylinder head setscrews on the Clark CMP50/60/70 forklift?
The cylinder head setscrews should be tightened in the specified sequence to 110 Nm (80 lbf ft) 11.1 kgf m. After this initial torque, they must be tightened a further part of a turn based on the setscrew length: 150° (2.5 flats) for short setscrews, 180° (3 flats) for medium, and 210° (3.5 flats) for long setscrews. p. 72
What are the valve tip clearance specs for the Perkins engine in the Clark CMP50/60/70 forklift?
With the engine cold, the valve tip clearance for the inlet valves is 0.20 mm (0.008 in) and for the exhaust valves is 0.45 mm (0.018 in). p. 41
How often should the transmission oil filter be changed?
The transmission oil filter should be changed every 500 hours of operation. Additionally, it is recommended to change the filter after the first 50 and 100 hours of operation on new, rebuilt, or repaired units. p. 280
What is the correct procedure for bleeding the service brakes?
Service brake bleeding requires two workers: one to depress the pedal and the other to bleed the system. Fill the reservoir with SAE DOT-3/DOT-4 brake fluid, attach a clear vinyl hose to the axle wheel end bleeder screw, depress the pedal to build pressure, and loosen the bleeder screw while the pedal is depressed to release air. p. 334
Will this Clark CMP50 Service Manual download right away?
Immediate download of the complete 411-page searchable Service Manual. Access it on any device, from a laptop at your desk to a phone in the field.
Am I free to print this Clark CMP50 Service Manual?
Yes. No DRM, nothing blocks printing, so run off the pages you need on whatever printer you have.
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