Description

Thomas 250, 255 Parts Catalog – Factory OEM Parts Breakdown

I’m Mike Callahan. The Thomas 250, 255 Parts Catalog is a 148‑page OEM parts breakdown for these skid steer loaders. No guesswork.

Fuel System Parts: Chapter 1.1 Breakdown

Turn to page 1 and you’re looking at the mainframe section. The fuel system subsection lists every component from the tank through the lines. When you’re ordering a replacement fuel line for a 250 or 255, this book gives you the exact part number. I’ve seen guys order the wrong fuel filter housing because they used a generic cross‑reference. Don’t. The manual shows the correct Thomas part for your machine’s serial‑number range. Internal Combustion Engine manuals give you the repair procedures; this book gives you the parts that go back in.

7 Systems Covered: From Mainframe to Optional Equipment

The manual covers eight chapters: Mainframe, Controls, Final Drive Transmission, Hydraulic System, Hydrostatic Drive System, Electrical System, Engine Equipment, and Optional Equipment. That’s the full machine—from the ROPS assembly down to the tilt cylinder. The optional equipment section alone runs 28 sub‑sections, including cab enclosures, block heaters, backup alarms, and self‑level valves. If your machine has a two‑speed option or a suspension seat, the part numbers are there. The index on page 2 shows you where every system lives.

Hydraulic System Components: What the Manual Covers

The hydraulic system section (chapter 4) includes the oil reservoir, filter, boom lift circuit, bucket tilt circuit, auxiliary circuit, control valve, and accumulator. There are separate subsections for the 250 and 255 models. For example, the lift cylinder on a 255 is a different part than on a 250—the manual breaks them out. Same for the tilt cylinder. If you have a machine with the optional self‑level valve, there’s a dedicated subsection (4.3 (A) and 4.6 (A)). Also note the fan/radiator/oil cooler split at serial number LR000185. You need to check your S/N tag to pick the right diagram. The electrical system section (6.1 and 6.2) covers wiring harnesses for the ROPS and engine, including connector part numbers. If your machine has a CAN Bus Network for optional controls, the manual lists the connectors and harness identifiers.

Is This Manual Only for the 250 and 255 Models?

Yes, this parts catalog is specific to the Thomas 250 and 255 skid steer loaders. That’s a good thing. A dedicated catalog means no hunting through generic sections. Many components share part numbers across these two models, but where they differ—like the fenders (section 1.10 for 255 models only) or the hydrostatic drive circuit (5.1 vs 5.1 (A))—the manual makes it clear. The back of the book includes a numerical parts list, warranty info, and S/N tag locations. If you own a different Thomas model, check the related manuals below.

Get the Right Torque Data from the Factory

A parts catalog does not list torque specs—that’s what the service manual is for. But this catalog gives you every seal, gasket, and O‑ring part number you need when you’re reassembling the hydrostatic drive or the engine. Aftermarket parts lists often skip the crush washers and backup rings. This factory catalog includes them. Pair it with the Thomas service manual, and you’ll have the part numbers and the tightening sequences. The workshop tip: always order the seals listed in the manual before you start the tear‑down. Waiting for a seal during a rebuild costs you billable hours.

Source Authenticity: OEM Factory Print, Not Aftermarket

This is an original Thomas factory Parts Catalog, publication number 049483SP. It’s a direct scan of the printed OEM document. Aftermarket parts catalogs often transpose digits, skip revision levels, or combine multiple model years into one confusing chart. This catalog gives you the part numbers exactly as Thomas issued them. The warranty section and decal placement diagrams are included.

Can I use this manual to rebuild my Thomas 255 engine?

No. This is a parts catalog, not a service manual. It lists part numbers, not procedures.

How do I find a part number for the hydraulic oil filter?

Turn to Chapter 4, Hydraulic System, section 4.2 Hydraulic Oil Filter. The manual shows an exploded diagram with callouts. Each callout corresponds to a part number in the list. For the 250 and 255 models, the filter may differ. The manual includes both standard and optional self‑level valve variants. If your serial number is LR000185 or later, you need to reference subsection 4.4 (A) for the fan/oil cooler assembly. Cross‑check the part number against the S/N tag on your machine. The index on page 2 will guide you to the correct page. This is why you want the factory catalog — aftermarket catalogs often miss these serial number breaks. Also check the Optional Equipment chapter for the filter adapter (subsection 8.14 Hydraulic Oil Heater) if you have that option.

You’ve got the machine in the bay. Don’t order parts blind. Get the factory breakdowns, match the numbers, and get the job done. Thomas T-233 HD, T-203 HD, T-183 HD, T-173 Parts Catalog – OEM Parts Manual covers other Thomas skid steer models. Thomas 173 HLS II 1996 Parts Catalog – Factory OEM Manual and Thomas T245 HDK 2002 Parts Catalog – OEM Factory Manual are also available. Access the Factory Manual now.

• Thomas T-233 HD, T-203 HD, T-183 HD, T-173 Parts Catalog – OEM Parts Manual
• Thomas 173 HLS II 1996 Parts Catalog – Factory OEM Manual
• Thomas T245 HDK 2002 Parts Catalog – OEM Factory Manual