Braking with radial piston motors

[hydroman247]

Hi guys, got what is probably a simple question for you.

Radial piston motors
Closed loop drive system.
Hydraulic brakes
PM is an electric motor which is on/off as you use the machine.

The issue as you can imagine is when driven up a slope and the motor is stopped, the radial piston motors do not like this. Not to worry, we have the main brakes to hold the machine steady. When we come to set off again, as the brakes release, we roll back a foot before sufficient pressure has built up to hold the motors steady again.

An expensive way around this might be pressure sensors on either side of the pumps closed loop and when we reach a certain pressure, then the brakes release but are there any other common solutions to this problem?

Thanks

 

[PersonalProfile]

I was just thinking about this a bit more, technically an analogy for the performance you require would be a hydraulic winch, of which there are numerous successful examples.

Regards,
Lyle

 

[hydroman247]

This is a mobile machine that needs to drive forwards and backwards. It weighs ~3000kg.

I have attached a pressure log showing the pressure drop on the "B" side. The higher pressure is on the "A" side being squeezed by the wheel motors and the pump.

 

[PNachtwey]

An expensive way around this might be pressure sensors on either side of the pumps closed loop and when we reach a certain pressure, then the brakes release but are there any other common solutions to this problem?

I have seen the objections to the electronic controls but I have this modeled out so that braking can be done very precisely by monitoring and controlling the pressure drop across the motor. I know you consider this to be expensive but what is time and performance worth?

Our engineers can control and tune systems over the internet using gotomeeting or gotoassist and configure and tune systems anywhere there is an Ethernet connection. Resistance is unprofitable.



Peter Nachtwey
Delta Computer Systems

http://www.deltamotion.com

 

[hydroman247]

Cost is a large part of this project so at the moment we are not wanting to use any extra electronics.

We managed to make the issue a lot better by bringing the pressure reducing valve down so the pressure is enough to release the brakes but no oil is wasted stroking the brake cylinder further. The capacity of the brake cylinders was relatively large before, but now it seems a lot better. It also helps slow down the brake disengagement which gives the loop time to maintain pressure.