Description

DAF Bus Workshop Manual – TRW Steering Gears

I’ve seen it a hundred times: a guy cracks open a steering box, guesses at the poppet valve setting, then wonders why the bus wanders at highway speed. That’s a $2,000 mistake waiting to happen. The DAF Bus Workshop Manual stops that nonsense cold. 41 pages of factory procedure for TRW steering gears – not some third-party rewrite that leaves out the critical numbers. If you are wrenching on a DAF bus, either on the shop floor or in your own bay, you need this document open before you touch a single bolt.

DAF Bus Workshop Manual: 41 Pages of Factory Procedure

This isn’t a glossy brochure. It’s a scanned copy of the original workshop manual DAF released to its dealers. The table of contents is laid out like a real job: start with general information (page 1-1), then hit the technical data (page 2-1), then get into adjustments, removals, and installations. Every chapter is numbered exactly as DAF intended – which means when you call a parts supplier, you can reference the exact section they need to hear. No cross‑referencing aftermarket part numbers. No guessing.

Steering Gear Operation and the Recirculating Ball System

Section 1.1 explains how the recirculating ball mechanism drives the rack piston and how the torsion bar connects to the worm shaft. If you have ever rebuilt a power steering gear, you know the valve spool alignment is everything. This manual shows it visually on page 1-5 with the general view of the steering unit. Don’t treat this like a generic diagram – DAF engineered these tolerances for commercial bus loads, not passenger cars. Over‑torque the worm shaft seal and you have a leak that kills your day. Under‑torque and the gear slops out. Page 10-1 gives the exact worm shaft seal removal and installation steps. Follow them.

Poppet Valve Adjustment: Page 3-1 Procedure

The poppet valve controls the hydraulic assist cut‑off. Get it wrong and the steering either locks on a turn or blows through the relief valve. The manual dedicates a whole chapter – section 3 – to this single adjustment. It lists the special tools required (page 2-3) and the exact measurement sequence. I don’t care how many steering gears you have done; if you skip the poppet valve calibration, you are asking for a comeback. OEM spec is spec. Period.

Technical Data and Special Tools – What You Get

Page 2-1 holds the raw numbers: fluid capacities, pressure settings, torque values for every fastener on the steering gear. Need the relief valve cracking pressure? It’s buried in section 8. But the technical data table is where you start. I keep a printed copy taped inside my toolbox lid. Also listed: the specialized pullers and wrenches DAF expects you to use. You can sometimes fudge a tool with a brass drift, but for the pitman arm pull (section 5), you need the factory tool to avoid bending the sector shaft. The manual shows tool numbers – order them ahead.

3 Removal and Installation Chapters You’ll Use Most

Sections 5, 6, and 7 cover pitman arm removal, steering gear removal/installation, and steering gear support removal/installation. If you have done a steering gear swap on a bus, you know the chore of wrestling a 40‑pound assembly while lying on a creeper. The manual gives you the sequence: disconnect hydraulic lines first, mark the pitman arm position, support the gear, pull the bolts. Torque the mounting bolts in the pattern shown on page 6-1. No aftermarket manual includes that pattern – only the OEM print. One more thing: section 8 deals with the relief valve. If your bus has a stiff spot in the turn, that valve is likely contaminated. Replace it per page 8-1, not with a generic clean‑and‑reinstall. Paper gaskets are cheap; downtime is not.

Why OEM Documentation Beats Aftermarket Reprints

I have seen aftermarket manuals that claim “covers all TRW gears” and then drop a torque value that is off by 10 Nm. That 10 Nm on a steering gear clamp bolt is the difference between a gear that holds alignment and one that creeps. DAF printed this document for its own service network. The drawings are correct. The callouts are consistent. There is no “typical” or “may vary” language. Internal Combustion Engine principles are not directly covered here, but the steering gear interacts with the engine’s hydraulic pump – and the manual includes the pump flow specifications in the technical data. Also note: if you are also working on the Manual Transmission system, stop guessing and grab the matching DAF transmission manual. This steering manual stays focused on the gearbox itself.

Related manuals that pair with this one: DAF SBR 3015 Workshop Manual – Steered 3rd Axle Repair Guide for tandem‑axle buses; DAF LF45, LF55 2010 Workshop Manual – OEM Factory Specs if you have a rig with the LF chassis; and DAF LF45, LF55 2003 Workshop Manual – OEM Steering & Axle Specs for older power steering systems. All original DAF prints – no reprints.

How many pages does the DAF Bus Workshop Manual have?

Forty-one pages.

Does it cover the entire DAF bus or just the steering gear?

This manual is specific to TRW steering gears used in DAF buses. It covers the steering unit, valve adjustments, sealing, and removal/installation of the gear, pitman arm, support, relief valve, sector shaft gasket, and worm shaft seal. It does not cover engine, transmission, or suspension systems. For those, you need the corresponding DAF service manuals.

What torque specs are included?

Section 2.1 on page 2-1 lists torque values for all steering gear fasteners in Nm. The manual also includes the poppet valve adjustment force and gear play preload. You must use a torque wrench – do not guess.

Is this a reprint or a factory original?

This is a scanned copy of the original DAF factory workshop manual. It is not an aftermarket summary. The document includes DAF’s own part numbers, copyright notice, and revision dates. You are getting exactly what DAF issued to its technicians – no omissions.

You can stop burning hours on bad information. Get the factory procedure, follow the sequence, and button up the job right. Access the Factory Manual and keep it hammer‑accessible in your shop.