Question for fine tuning my homemade 6 wheel skid steer

justinlovestobuildstuff · Sep 24, 2017

Hello again everyone, its was a few months back when i posted for help about my creation.

http://www.tractorbynet.com/forums/hydraulics/382900-homemade-6-wheel-drive-cart-new-post.html

I have since bought a smaller pump/larger motors and it seems to be working pretty well. I have moved hundreds of pounds of dirt up a very steep incline without feeling sore the next day. I'm now dealing with runaway motor issues and before purchasing crossover valves and hoses I would like some input.

The situation- so when going down my very steep hillside the cart will sometimes runaway completely, with the control valves in the forward moving position or neutral (closed). I can open the valves to go backward and this does stop the cart immediately but i know this is terrible for the components of the system. If i descend very slowly the cart becomes jerky as if i can feel each revolution of the motor as they're being turned by the load (the wheels and weight of the cart) but all of a sudden it picks up speed even if i let go of the control valves. I assume the motors are experiencing cavitation because both inlet and outlet ports are blocked at this point.

Before I spend the time and money for crossover/cushion valves I just want to make sure they will provide the slow and controlled descent im hoping for. I have ordered a flow control valve (with relief) and will dial back the flow while descending.

Surplus Center has two listed 500-1500psi or 1500-3000psi. I have my system pressure limited to 1800 psi (17cu" motors max rating) and im wondering which ones would be suited best for my application.

As always thanks for your time and input.

oldnslo · Sep 24, 2017

You are describing the function of counterbalance valves. These are designed to reduce or eliminate runaway conditions. I would suggest a pilot ratio of 8:1 or 10:1 for use on motors. When set properly these will provide a controlled braking action while going down hills.

justinlovestobuildstuff · Sep 24, 2017

oldnslo said:
You are describing the function of counterbalance valves. These are designed to reduce or eliminate runaway conditions. I would suggest a pilot ratio of 8:1 or 10:1 for use on motors. When set properly these will provide a controlled braking action while going down hills.

Excellent thank you, I figured they would do the trick. I suppose the 1500-3000 psi is a better choice? The motors intermittent rating is actually 1600 psi but im pushing the pressure just a tad more (1800psi) for those extra heavy uphill loads.