Description

Clark-hurth SM 538, NS 246, NP 246 Service Manual

I see a lot of guys trying to rebuild these old Clark-hurth lift trucks with a Chilton’s and a prayer. That’s how you turn a $500 job into a $5,000 parts bill. If you are working on an SM 538, NS 246, or NP 246, you need the real factory documentation – not some third-party rewrite that leaves out the critical fastener torque check. This Clark-hurth SM 538, NS 246, NP 246 Service Manual is the exact 188-page binder that Clark dealers used. It tells you the order of operations, the tooling required, and the torque values that keep the fasteners from backing off or stripping out. No shortcuts, no guessing.

Critical Fastener Torque Check – Why the PM Section Matters

Group PM (Planned Maintenance) includes a dedicated procedure called “Critical Fastener Torque Check.” Clark-hurth designed these lift trucks with specific torque sequences on drive unit bolts, brake mounting hardware, and steering gear fasteners. The manual gives you the numbers in ft-lbs – not “tighten until it feels right.” If you skip this step during a rebuild, you risk a wheel parting company with the axle at operating speed. I have seen it happen. The PM section also covers visual inspection, functional tests, and a test drive procedure. That last item is something aftermarket manuals always omit. You need to know what the truck should feel and sound like after service.

SCR Control and Symptom Charts – Electrical Diagnostics

Group 19 covers the SCR control system, recommended test equipment, and symptom charts. If the drive motor won’t engage or the lift pump runs slow, you go straight to those symptom charts. They list causes like bad contactor tips, failed SCR modules, or low battery voltage. The manual shows you how to test each component with a multimeter and gives the resistance ranges. Following the chart in order saves you from swapping parts until the wallet is empty. The control panel disassembly and contactor inspection procedures are also here – page 12-01 for battery removal if you need to isolate power first.

Drive Unit Disassembly and Inspection

Group 20 is the drive unit – the heart of the truck. The manual lists required tools (pullers, presses, dial indicators) before you even start. Drive unit removal, disassembly, inspection, assembly, and installation are all separate sub-sections. You get the bearing clearances, gear backlash specs, and the order of shim placement. If you have ever rebuilt a differential blind, you know that missing one thrust washer can wipe out the whole carrier. This manual gives you the checkpoints so you don’t have to learn that lesson twice. The torque values for the ring gear bolts are listed in the inspection section.

Battery Handling and Care – Safety First

Group 12 is not just a few bullet points about wearing gloves. The manual goes through battery removal procedure step by step, including the sequence for disconnecting cables to prevent arcing. Battery maintenance, record keeping, and installation instructions are also here. A lot of DIYers don’t realize that a fork truck battery weighs over a thousand pounds. The manual tells you what sling configuration to use and how to avoid pinching the cables. For an overview of manual transmission principles, see Manual Transmission on Wikipedia. But for the specific battery specs on these Clark-hurth models, stick to the factory book.

Steering System and Power Steering Pump

Group 26 covers the steering system, including the torque generator removal and disassembly. The power steering pump section includes a relief pressure check procedure. If you are getting hard steering or wandering, the manual gives you the pump troubleshooting chart and the steps to test pressure at the relief valve. The pump inspection criteria – shaft wear limits, vane condition, and seal replacement – are all spelled out. Do not use aftermarket specs here; they are often generalized for multiple models and can be off by 100 psi. Stick with the Clark-hurth data from page 40-02 where the truck specifications are compiled.

Related Manuals

• Spicer Clark-hurth HR Service Manual – Factory Specs for Heavy-Duty Transmission
• Clark-hurth 55A SERIES II Service Manual – 136 Pages of Factory Specs
• Clark-hurth SM-715, TMX12-25, EPX16-20s 2007 Service Manual – 502 Page OEM Facto

Does this manual include torque specs for the drive unit?

Yes – torque values for ring gear bolts, axle flange fasteners, and wheel lug nuts are listed in the Drive Unit inspection section (Group 20).

What tools do I need to follow the steering system rebuild?

The manual lists a puller set, dial indicator, torque wrench (0-250 ft-lb range), and a press. For the power steering pump relief pressure check, you need a pressure gauge that reads up to 2500 psi. The test procedure (Group 26) includes the exact hose connections and valve positions. Do not skip the shaft/gear removal steps – the manual shows you how to hold the gear to prevent damage while pressing the shaft. If you do not have the gear holding tool, you can make one from a piece of bar stock per the dimensions given. There is also a separate section on caster adjustment (Group 25) that affects steering feel. Missing that step will cause uneven tire wear. So, the tool list is specific, but the manual gives you alternatives where possible. For a general explanation of manual transmission concepts, see Manual Transmission. But for torque values on the steering column bolts, trust the factory book.

Look, I have been turning wrenches for 28 years, and I still reach for the factory manual every time I touch a piece of industrial equipment. Aftermarket knock-offs leave out the safety checks and torque sequences that keep you from getting hurt. This Clark-hurth service manual is the real document – 188 pages, OEM content, and organized the way Clark intended. If you are going to rebuild an SM 538, NS 246, or NP 246, do it right. Access the Factory Manual from AutoRepairManuals and keep it in your shop tablet. You will reference it on every job.