Description

Clark-hurth HR Service Manual – 64 Pages of Factory Specs for the 28000 Powershift Transmission

You’ve got a Clark-hurth HR model 3-speed short drop transmission sitting in the bay, and it’s either leaking, slipping, or dead. The last thing you need is a generic PDF that guesses on clutch clearances or tells you to “tighten until snug.” I’ve seen what happens when someone uses aftermarket torque specs on a 28000 – stripped ring gear bolts and a comeback that costs you a Saturday. This is the real deal: the actual Clark-hurth HR Service Manual, 64 pages, printed from the same plates Clark used back when they were building these. No corporate disclaimers about “approximate values.” Every figure, every sequence, every torque spec came off the assembly line in Statesville, NC.

Transmission Disassembly – Page 1: Where the Real Work Starts

Page 1 kicks off with the actual disassembly procedure. Not a generic “remove bolts” overview – it walks you through pulling the converter, separating the case groups, and dealing with the clutch pack without dropping needle bearings into the sump. The manual calls out the order so you don’t jam a pry bar where the charging pump lives. If you’ve ever fought a seized clutch hub, you know why this sequence matters. Skip a step? You’ll be ordering a new case because you cracked the register. I’ve got a junkyard story for that, but I’ll save it.

Regulating Valve and Charging Pump – Fig. F & G

Look at the sectional views – Regulating Valve, Charging Pump and Filter Group (Fig. F) and Control Valve Assembly (Fig. G). The manual doesn’t just label parts; it shows the internal passages and spring positions. When you’re chasing a no-forward condition, you need to know which orifice feeds the clutch apply circuit. Aftermarket diagrams always skip the cross-drilled passages. This manual pins them exactly. Page 27 lists the charge pressure spec – you can verify pump output without guessing whether the regulator spring is weak. That saved me three hours on a backhoe last year.

Brake Service – Mechanical Parking Brake Fig. H

The mechanical parking brake on these HR units is a common failure point. The manual dedicates Fig. H to the assembly, and the rebuild section calls out the adjustment procedure. If you don’t set the shoe clearance to the factory gap, the brake drags and cooks the transmission oil. Page 26 (Servicing Machine After Transmission Overhaul) reminds you to check brake drag before you button it up. I’ve seen guys ignore that step and burn up a fresh clutch pack in 20 hours. Don’t be that guy.

Specifications and Service Data – Page 27

Page 27 is the cheat sheet every mechanic needs: torque values for everything from the converter housing bolts to the clutch cap screws. Oil capacity in quarts (imperial – they didn’t switch to metric on these). Recommended lubricant type. The adjustment specs for the shift linkage. You don’t have to flip back and forth because the manual grouped them in one spread. Want the main relief valve pressure? It’s there. Need the cooling flow rate? Also there. This is the page you laminate and tack to the toolbox.

Troubleshooting Without Guessing

The Trouble Shooting Guide on pages 27-28 covers the common headaches: low pressure, overheating, hard shifting, no engagement. Each symptom has a numbered list of causes and the corrective action. No vague “check hydraulic system.” It tells you which valve to pull, which plug to remove, and what pressures to expect. If you’re working on a 28000 in a skid steer or a forklift, this guide will get you to the root cause in half the time. Pair it with the Manual Transmission Wikipedia article for background theory, but trust the factory sequence for repairs.

Source Authenticity – Why OEM Beats Aftermarket

I won’t name names, but some third-party manuals are photocopies of a copy with blurry torque specs and missing pages. This one is an original OEM print from Clark-hurth. Look at the copyright: 1992, Clark Equipment Company, unpublished material, limited distribution. That means it was never intended for the public – it went to dealers and fleet shops. The Spicer Clark-hurth HR Service Manual – Factory Specs for Heavy-Duty Transmission is the same quality. If you’re rebuilding the HR, you need the original. Period.

Related Manuals You Might Need

• 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
• Manual Transmission – general background reading

Does this manual cover the HR model with the short drop?

Yes – the cover says “HR MODEL 3 SPEED SHORT DROP.” All 64 pages are specific to that configuration, including the converter assembly and plumbing.

What about the control valve rebuild – does it give the spring specs?

Spring free length and installed height are not listed in spreadsheet form, but the sectional view (Fig. G) and the reassembly instructions on page 13 describe how to check spring tension against the valve body. For exact spring part numbers, you’ll need the parts manual listed in the foreword. The service manual tells you how to install everything correctly – pages 13 through 26 cover reassembly in sequence, including the clutch pack clearance checks and the ring gear installation (Fig. M). If you follow the steps, you won’t need to guess on spring rates because the hydraulic system will test itself once you set charge pressure per page 27. I’ve done three of these in my shop, and the manual hasn’t steered me wrong yet.

Access the Factory Manual now – stop wasting time with knock-offs. This 64-page PDF gives you the same information Clark dealers used. You get the disassembly steps, the valve body diagrams, the brake adjustment, and the specs that make a rebuild last. No fluff, no reprints, just factory data.