Motor and relief valve selection

[DJNebraska]

You could mount the relief right to the motor.

Relief Valve Block Mounted to Motor

Relief Valve For Motor Mounted Manifold

You'd have to purchase the Surplus Center 9-4648 manifold anyway. Why not put the relief there instead? Eliminate some plumbing.

Ports are #6 o-ring instead of 1/2" pipe...don't know if that will change anything.

 

[Waratah15]

Well after going through all the math I've had a change of direction!
Now I'm planning to instal a high speed motor onto the end of the flail shaft, it won't actually protrude all that much further than the existing belt cover and I'll make a very sturdy guard for it so it doesn't get damaged in use.

The motor I'm looking at is this one

Surplus Center - 1.95 cu in CROSS HYD MOTOR 50MH19DBCSC

At 17 gpm it is doing 1800rpm which is high but fine for the bearings.

To protect the motor I was planning to use one of these cushion/relief valves

Surplus Center - 1/2 NPT 30 GPM 1500-3000 PSI HYD CUSHION VALVE

Again, very hard to find any information on the valve and the circuit required, would really appreciate if someone with experience could describe the circuit I require to use this valve. Seems like there are actually two circuits running through the valve, but not sure.

Reason for the change of heart is that driving direct simplifies the whole thing and I'll get rid of all the power loss through the gearbox and the belts. Seems to be reasonably common practice to power flail mower shafts directly in the mowers designed to work on an arm for roadside clearing.

I'll end up with a cutter speed of approx 4500 fpm, should be fine forthe scrubby stuff I'm planning to cut.

Thank you for all the advice so far, greatly appreciated.

Jonathan

 

[J_J]

I computed about 2,014 rpm, and should provide a high blade tip speed.

You don't need a double relief valve unless you are going to reverse the motor.

Here is a picture of a motor with a double relief valve.

B and D go to motor, and A and C go to work ports on valve.

http://www.surpluscenter.com/Drawing/DR9-4019-50-H.pdf

If you can't see the small drawing, I use the CTRL key on my keyboard. I hold down the CTRL/control key and roll the thumb wheel and it will magnify the whole page.

http://www.baumhydraulics.com/files/catalog/h13.pdf

 

[oldnslo]

The cross over or dual relief could be used for wind down or controlled stop of the flail mower. Not sure if you have a motor spool on your remotes or not.

The relief that goes from inlet to tank you would set to protect the motor from stalling and shock loads.

The relief that goes from outlet to inlet you could set at some low value that allow the flail to free wheel down under load. This would prevent the possible sudden shock of closing the main spool if it is not a motor spool.

Roy

 

[Waratah15]

Don't know if I have a spool valve on the auxiliary circuit but putting in the dual relief valve sounds like cheap insurance.

So all I need to do is run both auxiliary lines straight through the valve and onto the motor.

Thank you once again for your help gentlemen