Clark C500-35 through C500-55 Forklift Factory Service Manual (P/N PMA-273)

• Document identity: A 335-page PDF of Clark Planned Maintenance & Adjustment Procedures, publication PMA-273, 10th Revision, with incorporated pages dated from October 1973 through May 1984.
• Machine coverage: Applies to the C500-355 series in Hydratork, Hydracool, pneumatic-tire, and cushion/solid-tire configurations: C500-35/40/45/50/55/S60, H30/H40/H50, Y40/Y45/Y50/Y55/SY60, and HY40/HY50.
• Engine and drivetrain procedures: Covers gasoline/LP-gas engine tune-up and fault isolation, fuel-pump testing, carburetor and governor adjustment, clutch-pedal adjustment, and Hydratork 1- and 2-speed stall, pressure, aeration, cooling, and drain/refill checks.
• Hydraulic, steering, and brake work: Includes main-hydraulic and steering pressure tests, steering-gear and linkage adjustment, manual and pressure brake bleeding, service/inching-pedal setup, brake-adjuster checks, and parking-brake adjustment.
• Upright repair coverage: Provides lift-chain inspection and adjustment, carriage removal and installation, roller and rail shimming, load and cylinder-drift tests, and disassembly/reassembly procedures for standard, Hi-Lo, and six-roller full-free-lift triple-stage uprights.
• Chassis maintenance: Details pneumatic and split-rim wheel service, steer-wheel bearings, axle-end lubrication, driver-restraint inspection, counterweight removal, cooling-system maintenance, starter/alternator checks, and neutral-start-switch adjustment.
• Factory reference data: Supplies lubrication charts, approved-fluid guidance, capacities, component torque tables, pressure-test specifications, electrical test data, wear limits, inspection forms, an internal-combustion wiring color code, and illustrated test hookups.

Planned Maintenance Overview

Clark divides the program into a shift-start driver inspection and a scheduled planned-maintenance routine. The normal PM window is 50 to 250 operating hours, adjusted for operating conditions. Inspection sheets cover leaks, fluid levels, tires, lift and tilt operation, steering, brakes, controls, warning devices, guards, chains, and restraint equipment. The maintenance sequence adds cleaning, lubrication, filter service, and minor adjustments.

Clark states that maintenance, repair, adjustment, and inspection are to be performed by qualified and authorized personnel. This manual is therefore suited to experienced lift-truck technicians with normal shop tools, pressure gauges, lifting equipment, and the training needed to work around raised uprights, hydraulic pressure, counterweights, and multi-piece rims.

Engine, Transmission, and Hydraulic Coverage

The engine material is built around Clark engines with 155- and 176-cu.-in. displacement. It uses charging, cranking, compression, ignition, fuel-delivery, vacuum, hydraulic-load, and transmission-stall checks to separate an engine problem from a converter, clutch-pack, or hydraulic fault. Separate procedures address Zenith gasoline and LP-gas carburetor/governor adjustment, mechanical fuel-pump testing, ignition timing, distributor and spark-plug service, valve-tappet inspection, and governed-speed checks.

For the drivetrain, the manual distinguishes Hydratork 1- and 2-speed testing from the H and HY clutch-pedal adjustments. It covers Hydratork stall and oil-pressure diagnosis, neutral-start-switch operation, fluid aeration, leakage, cooler-flow restriction, and common-sump drain/refill service. Hydraulic and steering sections add gauge hookups at the pump or control valve, main-system relief checks, power-steering pressure diagnosis, steering-gear adjustment, linkage geometry, wheel-bearing adjustment, and lift/tilt cylinder drift evaluation.

Upright and Chassis Procedures

The standard and Hi-Lo upright material includes carriage removal and replacement, six-roller carriage setup, upright roller clearance, lift-chain wear and tension checks, tilt-cylinder adjustment, and operational testing. Incorporated PMA-321 and PMA-345 procedure sheets extend that coverage to full-free-lift triple-stage uprights with six-roller carriages and M-series deck numbers. That triple-stage section is expressly scoped to uprights used on trucks rated from 2,000 through 12,000 lb and covers latch operation, intermediate-rail and carriage chains, roll-pattern inspection, cylinder-seal checks, racking, capacity-load tests, rail-to-roller measurement, upright disassembly, reassembly, and final load testing.

Shop-aid content includes inside and outside spanning-tool drawings, upright calipers, a marking block, and pressure-gauge/tachometer setups. The caliper/marking-tool sheet identifies Clark hardware P/N 156-416, 190-416, and 160-04. Named references include the Hydratork stall-and-pressure test chart, transmission aeration and cooler-flow layouts, steering and main-hydraulic pressure hookups, the internal-combustion wiring color code, and rail-to-roller clearance views.

Specifications, Repair Cautions, and Scope

The specification tables distinguish base C500-355 hydraulic data from Y355, H355, and HY355 configurations. They identify main-system relief changes at lot 3611 and lot 3616, plus a tilt-cylinder rod-end torque change at lot 5270. Other tables cover tune-up data, capacities, approved fluids, steer-axle geometry, tires, and component torque values.

The cautions explain real damage mechanisms: reversed charging-circuit polarity or an open alternator circuit can damage the alternator and regulator, while incorrect carriage or rail-roller adjustment can score or gouge the upright roller paths. Blocking and restraint requirements are integral to the upright, counterweight, hydraulic, and wheel procedures.

This is a planned-maintenance and adjustment manual with selected repair procedures, not a complete engine, transmission, or axle overhaul manual. Its strongest coverage is inspection, diagnosis, pressure testing, scheduled service, adjustment, and upright work for the listed C500-355 configurations.