Motor control valve?

[Borisw37]

I'm sourcing a valve to control a hydraulic motor. The motor is for wheel drive, so I need to be able to vary the speed smoothly (not just on/off) and it needs to be reversible.
What should I look for in the valve specs. From what I gathered it needs to be 3 position, 4 port, but what defines it as a "motor" valve that can smoothly adjust the flow from zero to max?

Thank you,

Boris.

 

[J_J]

You can jerk a hyd motor using with a standard hyd valve, but you will not have fine/smooth control over the motor.

That is gong to be hard to do unless you get a proportional motor solenoid valve, and they ain't cheap

I have one of these valves to control my hyd PTO motor, and it is as smooth as I can move it.

It controls in one direction, but if you had a reversing valve coupled to it, you could use it.

Surplus Center - 3/8 NPT HYD FLOW CONTROL VALVE W/RELIEF RDRS137-08

This valve is for 0 - 8 GPM's. They make larger GPM valves.

Surplus Center

Also, if you had the pump and valve in the same assembly that would work, as most zero turn mowers have this setup.

Eaton Light Duty Transmissions


Eaton Light Duty Transmissions
Models 6, 7, 11

These transmissions combine a variable displacement, radial ball- piston, and hydraulic pump with a fixed displacement, radial-ball-piston, and hydraulic motor in one housing.
Applications: Lawn tractors (8-20 HP) and seeders, commercial mowers, golf course maintenance equipment, concrete saws, utility trucks, garden tractors and ZTR (zero-turn radius) mowers.
Specifications: Models 6 & 7 – Speeds (Max.) Input 3600 RPM, Output 2150 RPM. Torque Output: Continuous, 120 lb-in, Intermittent, 180 lb-in, Peak, 240 lb-in. Model 11– Speeds (Max.): Input 3600 RPM, Output 0 - 1950 RPM. Torque Output: Continuous, 360 lb-in, Intermittent, 540 lb-in, Peak, 720 lb-in.

http://www.hydraulic-supply.com/html/productline/mfgprod/eaton-transmissions.htm

 

[J_J]

My hydraulic Power-Trac uses 4 hyd motors, and is controlled by one of those Eaton variable speed pumps in a closed hydraulic circuit.

Output from the hyd wheel motors flow back to the INPUT of the pump, and a charge pump keeps the circuit full and provides through the pump to a radiator.

A pedal is used to go fwd or reverse at variable speeds.

You will need a tank equal to the pump flow,maybe more for extra cooling.

 

[oldnslo]

Boris,
You can purchase valves that have built-in pressure compensation modules that aide or help with shift smoothness but this ultimately comes down to the operator. Even zero turn mowers or skid steers will skid or spin the tires if the controls are moved to fast.

Since this is a wheel drive motor you will also have to consider some form of braking / runaway prevention device.