1995 Timberjack 450C Cessna Spool Valves

[Chris Harrell]

I am the proud owner of a 1995 Timberjack 450C Grapple Skidder that has done everything I have asked of it since acquiring it 9 years ago. I have since rebuilt the Cummins motor and the Clark tranny and am now looking at having to freshen up my hydraulics. Three years ago my grapple control and blade control spool valves started puking significant amounts of hydraulic oil (about 3/4 of a five gallon bucket per ten hour day) out the tops of the spool valves which led me to replace the o-ring and seal kit. The seal kit stopped the leaking and all of the cavitating and extra heat associated with the blow by. Three years later the spools are starting to leak again and am fighting lack of hydraulic pressure and complete loss of hydraulic power when the machine hits the higher temperature bands. I am wondering if there is something greater going on here and maybe need to be looking at rebuilding the valves; problem being is that the valves are now pushing 30 years old and am having a hard time finding replacements. There is a company in Seattle WA, HRD that specializes in and has said I may be needing to re bore the valve and re chrome the spools in the event the spools are worn out and the bores are bad and due to the fact that it is very hard if not impossible to find rebuilt Cessna valves. Do you guys have any ideas? Thank you for your help!

Chris

[Riwaka]

If the re-chroming of the spools is not good enough, you are likely to still have problems.

https://www.precisionfluidpower.com/cessna-hydraulics/

How well does the skidder's oil cooling work, does the system need an upgrade/ overhaul.
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If the valve needs replacing, you would need to measure up the dimensions, flow etc which matches best off the shelf.  

hydra-force
HydraForce - Hydraulic Cartridge Valves, Custom Manifolds and Electro-Hydraulic Control Systems

http://ph.parker.com/us/en/valves

Mobile Valves - Hydraulic Valves - Eaton

Valves - For heating, cooling and mobile hydraulics | Danfoss

Mobile Hydraulics | Bosch Rexroth USA

Might able to 3D print yourself a replacement valve bank one day.

3D printing hydraulic components
Aidro 3D printing hydraulic manifold: Design and Production - YouTube