Description

Clark-hurth NPR-345, NPR-17, NPR-20 Service Manual

If you are wrenching on a Clark-hurth NPR-17 or NPR-20 forklift without the factory binder, you are burning time on shots in the dark. Generic lift truck manuals skip the specifics that keep these electrics alive – things like the exact Clark-hurth NPR-345, NPR-17, NPR-20 Service Manual lays out. I have seen too many guys slap a generic battery section on a 36-volt traction motor and wonder why the brushes fried inside a month. This 492-page OEM document gives you the factory step-by-step, including the torque specs and test procedures that aftermarket reprints always leave out.

Battery Service: Keep It Alive

Section 12-1 covers battery handling, removal, cleaning, and charging – but it also includes a warning label about electrolyte and a section on keeping battery records. You want maximum life out of a battery? The manual tells you how to log charge cycles and electrolyte levels. Page 12-1-4 shows the recommended cleaning method using a baking soda solution and the specific gravity check procedure. Missing that step on a NPR-345 can kill a $2,000 battery in six months.

Electric Motor Service: 24 & 36 Volt Specs

Three separate sections (16-3, 16-5, 16-7) break down traction motors, pump motors, and auxiliary/steer pump motors for both voltage systems. Each includes a brush inspection chart, disassembly steps, and component troubleshooting. The 24-volt and 36-volt specifications are listed side-by-side – you get winding resistance values, brush spring tension, and commutator run-out limits. No guesswork. The manual explicitly says “When changing brushes” – it gives the break-in procedure and torque for the brush holder bolts. Use a 500-volt megger for insulation resistance, not a multimeter.

Brake System: From Linings to Bleeding

Five sections deal with brakes: Motor Brake (23-1), Caster Brake (23-2), Brake Bleeding Procedure (23-3), Brake Pedal Adjustment (23-4), and a section on Adjusting for Brake Lining Wear under Planned Maintenance. The bleeding procedure requires a specific sequence to avoid air entrapment in the dual-circuit system. Pedal adjustment tolerances are given in inches – free play between 1/8 and 3/16 inch. Skip that and you get dragging brakes or a pedal that bottoms out before full apply pressure.

Wiring Diagrams: Trace the Circuit

Section 19-6 provides the full wiring diagrams for the NPR-345 models. These are not generic schematics – they show the exact pinouts for the EV-T15 solid state control, the oscillator card settings, and the forward/reverse contactor wiring. The Electrical Sequence of Operation (Section 19-2) walks through every step from connecting the battery to plugging and travel speed limit. If you get a status code like -06 or -17, the manual gives the diagnostic path and which component to test first. Manual Transmission has its own wiring, but this is an electric truck – don’t confuse the two.

3 Reasons Factory Documentation Beats Aftermarket

First: torque values. The Specifications section (40-1-1) lists every fastener torque from the drive unit to the caster wheel – all in ft-lbs. Second: the oscillator card factory settings for both 24V and 36V trucks (section 19-4). Third: the lubrication chart (01-1) tells you the exact grease type and interval for every bearing, chain, and pivot point. Aftermarket manuals copy the diagrams but botch the numbers. This is the original dealer-only print.

Does This Manual Cover the Entire NPR Series?

Yes. The manual is explicitly titled for NPR-345, NPR-17, and NPR-20. The TOC includes specific sections for each model where they differ – like the 24V vs 36V motor specs and the NPR-345 wiring diagram (19-6). All three share the same chassis, upright, and hydraulic components, so the overhaul procedures for lift cylinders, tilt cylinders, and reach mechanisms apply across the board.

Source Authenticity: Only OEM Dealer Copies

This scan is from the original SM-587 published by Clark Technical Publications in Lexington, KY. Page 1 states “Intended for CLARK dealers only – Do not sell or distribute”. It is watermarked as copyrighted material and comes with the full pictorial index, all 49 group sections, and the index pages. No scanned-from-a-copy quality loss. The PDF retains the original line drawings and torque tables. Compare that to a third-party reprint that often omits the wiring diagram foldouts or the oscillator card adjustment steps.

What Torque Values Are Listed?

Section 40-1-1 (Specifications) contains the torque chart for all major fasteners: drive unit mounting bolts, wheel lug nuts, motor mounting screws, hydraulic fitting torques, and brake assembly bolts. You also get the lift chain adjustment specs (free sag in inches) and the caster wheel bearing preload. A dedicated table on page 40-2 gives service weights for the entire truck, which you need before using a lift or jack stands.

Does this manual cover the NPR-345 model specifically?

Yes. The manual includes a dedicated wiring diagram section (19-6) for the NPR-345, plus all three models share the same brake, battery, and motor procedures. The oscillator card settings list both 24V and 36V truck variants, which covers the NPR-345.

Can I use this to bleed the brake system?

Section 23-3-1 gives the full brake bleeding procedure. It requires a helper, a clear hose, and a catch bottle. The sequence is: start at the caster brake (furthest from master), then motor brake, then apply pedal slowly – two full strokes per bleeder valve. Torque the bleeder to 60 in-lbs after each cycle. Do not reuse fluid that has been bled out. The manual warns that contaminated brake fluid will damage the seals in the accumulator and master cylinder. Also, check the brake pedal adjustment (23-4-1) before bleeding, because if the pushrod is misadjusted you will never get a firm pedal.

If you want to keep these electric Clark-hurth trucks running without unnecessary downtime or parts failures, work from the original dealer documentation. Spicer Clark-hurth HR Service Manual – Factory Specs for Heavy-Duty Transmission covers the transmission models, but this one covers the electric drivetrain. Clark-hurth 55A SERIES II Service Manual – 136 Pages of Factory Specs is for the earlier internal combustion models. Clark-hurth SM-715, TMX12-25, EPX16-20s 2007 Service Manual – 502 Page OEM Facto is a later generation. For the NPR series, this manual is the one you need. Access the Factory Manual.