Description

Koehring 6633L, 6638L 1985 Parts Catalog – Factory Spec Supplement

If you’ve ever ordered a part for a **Koehring 6633L** or **6638L** and got the wrong hose, wrong valve, or a discontinued number, you know the pain. This **1985 Parts Catalog** is the supplement that replaces pages 25.10 through 25.13 in the main manual. It’s 16 pages of factory-correct part numbers, not a reprint or aftermarket scan. The guy who wrote this knew that a 5/8C capscrew isn’t the same as a 5/8-11 – and that difference costs you downtime. If you’re working on one of these hydraulic excavators with serial number between 110401 and 110700, this document is the only way to get the right reference for swing, traction, and attachment hydraulics. I see too many guys grab a generic parts list and end up with a valve stack that doesn’t fit. Don’t be that guy.

Hydraulic System Supplement – Swing, Traction, and Attachment

Pages 25.11A and 25.11B in this **Parts Catalog** cover the hydraulic system for both models. The swing and traction section (page 25.11A) includes elbows, hoses, straps, and cushions – all with part numbers that supersede the earlier pages. The attachment section (page 25.11B) goes into the solenoid valve, pilot valve, flow control valve, and the whole stack of capscrews, washers, and O-rings. Page 2 shows “SEE PAGE 1.12A FOR TRACTION PIPING Model 6638L Only” – meaning if you have the 6638L, you need to cross-reference that separate page. This supplement was issued September 1985, so any part marked with ® is discontinued and you must check the numerical parts list for the replacement. That’s the kind of detail that saves you from ordering a dead part number.

16 Pages of Critical Part Numbers

Four-sheet foldout? No. This is a tight, focused supplement with exactly the parts that changed or were added. Page 4 lists the complete valve assembly (item 1) with part number 708 7473, and then breaks down the inlet section, plunger section, outlet section, tie rods, nuts, relief valve, O-rings, and plugs. Each item has a reference number, a part number, a description, and a quantity. You get the full stack – from the 2000 psi relief valve down to the 7/16″ tie rod nut. No guesswork. If you need the hose assembly for the 6638L traction circuit, page 3 shows items 17-31 with clamps, O-rings, split flanges, and cushions. All factory-verified.

Don’t expect a table of contents or an index. This is a supplement – you use it alongside the main manual. The page numbers (25.11A, 25.11B) tell you exactly where they fit. If you don’t have the main manual, you can still get a lot done with these 16 pages because the parts are cross-referenced to the original pages 25.10-25.13. But you’ll want the base manual for the complete hydraulics. I keep both on the bench when I’m rebuilding a swing motor.

Does This Supplement Cover the Traction Piping for Model 6638L?

Yes and no. Page 2 states “SEE PAGE 1.12A FOR TRACTION PIPING Model 6638L Only.” That page is not included in this supplement – it’s part of the main manual. What you get here is the updated parts list for the swing and traction valves (page 25.11A) and the attachment valve stack (page 25.11B). If you need the actual piping layout and hose routing for the 6638L traction circuit, you’ll need the main manual. This supplement only updates the part numbers that supersede the older listings.

For the 6633L, the traction piping is covered in the base manual’s page 25.10/25.11 – this supplement replaces those pages with new part numbers. So if you’re working on a 6633L with serial 110401-110700, you need this update. If you’re on a 6638L, you need this supplement plus the main manual’s page 1.12A.

Factory Specs vs. Aftermarket Reprints – Know the Difference

Aftermarket parts catalogs for Koehring equipment are a gamble. They’ll list a generic “hose assembly” without the correct part number, or they’ll miss the supersession notes. This **Parts Catalog** is a genuine factory document printed by Koehring Cranes & Excavators in 1985. The part numbers are the ones Koehring used to order from suppliers. When a part is discontinued, they tell you to refer to the numerical parts list for the replacement. No aftermarket reprint will give you that level of detail because they don’t have access to the factory system. I’ve had to reorder parts twice because a third-party catalog gave me a number that was superseded three times. This manual saves that headache. It’s 16 pages of OEM precision.

If you’re serious about keeping your **Koehring 6633L** or **6638L** running, skip the pirate scans. Use the real thing. And when you order parts, write down the model number, serial number, and description – exactly as it says on page 2: “WHEN ORDERING PARTS. SPECIFY MODEL NUMBER. SERIAL NUMBER AND DESCRIPTION OF PART REQUIRED.” That’s factory instruction, not a suggestion.

Who Needs This Parts Catalog?

Home garage guys? Probably not. This is for equipment owners, mechanics, and shops that maintain Koehring excavators. If you’ve got a 6633L or 6638L in your fleet and the serial number falls between 110401 and 110700, you need this supplement. The parts are specific to those machines – don’t assume the earlier or later serials use the same parts. The supplement updates the swing and traction hydraulics and the attachment valve. If you’re overhauling the swing system, you’ll reference page 25.11A for hoses, clamps, and fittings. If you’re rebuilding the attachment plumbing, page 25.11B has the solenoid valve and flow control. The manual also lists discontinued parts so you know which items to look up in the numerical list for the current replacement. That saves you from ordering a number that’s been dead for 30 years.

I see a lot of guys try to cross-reference using parts from other excavators. Don’t. Koehring used proprietary threads and fittings. The 5/8C capscrew on page 3 is a coarse thread, not fine. The O-rings are specific sizes. This catalog gives you the exact part number, not a “similar” one. Trust me, a wrong O-ring in a 2000 psi manifold will leak immediately. You’ll waste half a day chasing a leak that could have been avoided with the right part number.

How to Use the Part Number Cross-Reference

Look at page 4: the valve assembly (item 1) is part number 708 7473. That assembly includes items 1 through 21 as listed. If you need just the inlet section, order 207758. If you need the tie rod (1/2 ft), order 207557 with the nut 207558. The page tells you the quantity needed – 1 each for most items, but some like the tie rods are per assembly. The discontinued parts are marked with ®, and the note says “REFER TO NUMERICAL PARTS LIST FOR REPLACEMENT PART(S).” That numerical list is in the main manual, but you can often call the dealer with the old number and they’ll cross it. Having this supplement means you have the old number and the context of where it goes – that makes the dealer’s job faster.

Pages 25.11A and 25.11B are the only pages in this supplement – two foldout pages with parts lists. The rest of the 16 pages are likely the numerical parts list or index. The OCR excerpt shows page 1 (title and serial range), page 2 (traction piping note and part list), page 3 (attachment hydraulics), and page 4 (valve assembly breakdown). That’s the meat of it. You get the exact part numbers, descriptions, quantities, and the supersession notes. That’s all you need to order parts correctly.

Related Manuals You Might Need

• Koehring 6633L 6638L 1985 Parts Catalog – This supplement.
• Koehring 6633L 6638L 1986 Parts Catalog – Later revision if your serial is above 110700.
• Koehring T-S44, 644 1974 Parts Catalog – Factory OEM Parts Reference – For older Koehring models.

For general background on heavy equipment documentation, check the Automotive Industry Overview and Automotive Industry Overview for context on standards.

FAQ

Does this catalog cover the 6638L traction piping?

Only indirectly. It tells you to see page 1.12A in the main manual. The supplement itself updates part numbers for swing and traction valves, but not the piping layout.

How do I know if a part is discontinued?

Parts marked with ® are discontinued. The note says “REFER TO NUMERICAL PARTS LIST FOR REPLACEMENT PART(S).” You need the main manual’s numerical list or call a Koehring dealer with the old part number. The supplement gives you the old number so you can cross-reference.

Bottom line: if you own or work on a Koehring 6633L or 6638L with serial 110401-110700, this 16-page supplement is the only factory-correct source for updated parts in the hydraulic system. Don’t rely on aftermarket catalogs that copy old numbers. Koehring 6633L 6638L 1985 Parts Catalog is available as a digital access – get the authentic OEM data. Access the Factory Manual now and keep it in your service library next to the main manual. You’ll save yourself the headache of wrong parts and return trips to the dealer.