L35/BT900 Hydraulic Working Pressure

[steveInMaryland]

So I have a L35 I bought used and all seemed well. I proceeded to dig up my first stump and noticed a stream/drip of pancake batter looking oil running down from the control valve. The water in the hydraulics is another topic coming soon.

Some investigation later I found the main pressure relief valve had a piece of heater core tube wrapped around it with a screw clamp. I assume to stop the leak.

Anyway; new relief valve is $257 plus from big K and only $67 from HUSCO. My question is what is the operating pressure of the BT900? The HUSCO valve is preset at 2000psi. I cannot find a setting for the Kubota part but my guess is 2000psi.

Anyone, anyone have a spec sheet or even better a spec sheet and hydraulic diagram for this awesome machine?

Thanks,
Steve

 

[lugbolt]

2480 to 2560 psi, IIRC. you'll want to double check the service manuals for the diagrams and how to test/set/adjust the pressures. It's easy to go overboard with the pressures...have had tons of them come into the shop with them "turned up" to over 3000 psi, they work harder that way. When they're not broken.

 

[steveInMaryland]

That is great info. The new HUSCO says each 1/4 turn on the relief is equal to 250psi. That makes it easy to guesstimate and not destroy this crazy powerful machine.

Man I love this site.

 

[steveInMaryland]

Some new info today.

The BT900 backhoes use HUSCO control valves but they are customized per Kubota specs so HUSCO Inc. is of little help. The main pressure release valves; #75595-63300, are HUSCO 51650-4 set at 2750 psi, 2 required. The secondary relief valves; #75595-63200, are HUSCO 5060-P set at 2500 psi and 4 are required. Strangely the stabilizer arms have no secondary relief valves so they are running at the full 2750 psi of the main valves.

As hard as I tried I cannot source the 51650-4 anywhere but tractor dealers and they run about $260.00. The 5060-P valves can be sourced fairly commonly for about $140.00 at places like Jerr-Dan dealers etc.

One of each type has rusted through and are spitting out a very fine stream of fluid whenever the machine is running. Stay away as it is potentially 3000+ psi the pump is capable of. I have it running leak free at the moment with some rubber oil line I split and worm clamped around the pin holes. Hardly ideal.

This post is mostly to get this info into the search archive for anyone needing it in the future.

If anyone has a source for better prices please let everyone know.

Cheers