Caterpillar DP55NM1 Forklift Service and Schematic Manual (99739-8B120)

On the floor or yard, a DP55NM1 is a diesel counterbalanced truck moving heavy loads through busy aisles and loading areas. When a second-shift breakdown stops that work, a warehouse maintenance tech or forklift mechanic reaches for this manual to find the fault, carry out the repair, and get the truck back before the next wave. I've used this kind of book when the truck has to leave the bay running, not waiting for a dealer visit.

What this manual helps you do

• Trace wiring, connectors, and electrical circuits through the truck schematics.
• Diagnose starting, charging, control, hydraulic, steering, braking, and transmission faults.
• Follow procedures for the mast, forks, lift hydraulics, axles, and power train.
• Adjust and verify service settings using the manual's workshop data.
• Rebuild or replace engine, drive-unit, hydraulic, and related truck assemblies.

Who this is for

This suits warehouse maintenance techs, plant maintenance teams, dealer technicians, independent forklift repair shops, and rental fleet mechanics. It is a workshop service manual for the forklift trade, with the operator handbook available as a companion volume.

FAQ

Q: What do I receive, and how is it organised?

A: You receive four Cat publications delivered as 29 PDF files, 864 pages total, split by section. The PDFs have a real text layer, so you can search and copy text, as well as print or zoom the pages at the job.

Q: Which trucks and serials does it cover?

A: It covers GP40N1, DP40NM1, GP45N1, DP45NM1, GP50CN1, DP50CNM1, GP50N1, DP50NM1, GP55N1, DP55NM1, and TB45. For DP55NM1, the stated coverage is serial AT28C-82011-up.

Q: How does it fit the repair work I'm doing?

A: This is the workshop reference for troubleshooting, service adjustments, schematics, and component repair on this Cat counterbalanced fleet. It gives the shop a practical route from fault finding to return-to-service work.

With this set in the bay, you can diagnose the truck, complete the repair, and put it back on the floor with less downtime.

Models covered by this manual

Caterpillar publication 99739-8B120 is the factory service and schematic manual for the DP55NM1, serial range AT28C-82011-up. The same publication covers 7 further forklift models: DP45NM1, DP50CNM1, DP50NM1, GP45N1, GP50CN1, GP50N1, GP55N1. The cover also lists GP40N1, DP40NM1, TB45. Check the model and serial number on your data plate before ordering.

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