MAGIC hydrauilics in Case Tractor

[subsearobot]

Hi,
I am looking at a CASE 5030. the hydraulic system has a requirement that I do not understand at all.

There are two manifolds- one for the drive and one for the bucket. When the bucket is removed, the pressure and return hoses that supply the bucket manifold need to be "shorted" together. If not, the gear pump runs up pressure until the relief valve cracks, heavily loading the motor and heating the fluid.

When no command is given, the prime mover "idles". As soon as a valve is actuated, the pump loads the prime mover. I am assuming that with no command, having P&T shorted, system pressure is 0.

This baffles me- if P & T are shorted, how does the system develop pressure (at the drive manifold) when there is a command from the drive manifold?

please enlighten me- I design simple hydraulic systems for subsea systems, and this "magic" absolutely has me baffled.

thanks in advance

 

[hydtools]

P and T are probably not connected together. A and B, the cylinder ports, are connected together so that if the bucket circuit is actuated flow will circulate without blocking the flow and loading the pump.

Ted

 

[MikeHalloran]

You're probably used to 'closed center' systems.
This sounds like an 'open center' system, which is more common in agriculture.
The valves are different inside.


Mike Halloran
Pembroke Pines, FL, USA

 

[subsearobot]

On reading further, it is a high-pressure carry over system.

You are correct- I use closed-center systems.

Looks like an opportunity to learn something new here. Isn't engineering great! If anyone has any reverences, I'd love to see them.

Thanks Mike

 

[hydtools]

I misread your original post.
You may have tandem pumps. One for the bucket and one for the drive. By connecting the bucket manifold P and T together you would make sure the bucket pump is never loaded by a dead-headed circuit so it does not cause the prime mover to load.
Power is then only available for the drive.
Is it a Case 5030 or a Ford/New Holland 5030?

Ted

 

[subsearobot]

Hi Ted,
It's a Case tractor- I think it's a 5030, but I could be wrong there.

cheers,
seton