Hydraulic question for the brain trust

I am in the research phase of a project that will incorporate a hydraulic motor. I have one here that runs a few hundred rpm. I want to use it to run a table back and forth (about 20’) It needs to be variable speed. Generally feeding will be slow, return fairly quick, but I may want to run it faster or slower as needed. The plan is to have a chain that is threaded through a hyd motor with the ends fasten to the table.

I am looking for a control valve that is kind of like an outboard boat motor control. When the handle is centered, the motor has no movement. Push one way spins the motor in on direction. Pull back it spins in the opposite direction. Both forward and back is like a throttle, the further you go the faster the motor spins.

I know they make such a thing because I have two in my skid steer. As the lever is pulled back the motor (wheels) begin to turn slowly. Pull it all the way back and it is spinning. I am not to concerned about load control as this will be operated manually and I can adjust for loading.

What the heck is that control called?

I have search;

Hydraulic speed control
Hydraulic motor control
Hydraulic flow control

Don't know the real name, but on Case garden tractors it's called the travel control. I've got a good used one if you're interested.

The version used by Case has 1/2" ID hoses and in stock form is used in a 9 gpm system.

The skid steer loaders I have come in contact with have either variable displacement hydraulic pumps (piston pumps) or variable displacement motors again piston or variable vane units. You normally move the swash plate in the pump which controls the flow to the motor which controls the speed. How often do you want tochange speeds? Also remember if you don't use a motor spool it will be very wise to put a cross over relief valve in the circuit. What drives your pump? Is the drive variable speed?

I used a valve like that for several years on a project I had made that used a hyd motor. Looks like a regular spool valve only there's no detent and it's pressure compensating, meaning it keeps the motor running the same speed regardless of the load. Maybe that would be called load compensation. I'm certainly no expert on the subject. Mr Schwiebert knows more about that than I do. Maybe he can fill in the gaps. Jim

The Surplus Center in Lincoln NE has a tec line that will help you design the system.(and sell you what you need)

You have expensive tastes.... The skid steer uses a variable displacement axial piston pump. When the swash plate (attached to the control lever) is centered the pump moves no oil. When you push it ahead a bit it moves some. When you push it full ahead it goes to full displacement. When you pull the lever back it reverses the direction of the plate which changes the porting of the pump and creates the reverse... or something like that.

I would think that if you can give up a bit of simplicity for a lot of cheap.... a 100 buck spool valve and a couple of 100 buck PC flow control valves would pretty well accomplish the same thing. Place a flow control in each output line of the spool to create a controled flow on the work lines and dump the excess back to tank. You'll get some feathering on the spool and the rest on the flow controls... A buddy of mine runs a sawmill carriadge like that and basically achieves any speed he needs just feathering the spool...


The axial piston pump you want is many thousands of dollars.

Rod

What you need is a rotary control valve.
Rotary control valve

Why noy use a two way valve like on a loader, cheaper and do the same thing. Orbit motor off reel drive on older JD combines works great and not so expensive!

A skid steer is hydrostatic and quit expensive to do. A simple 2 way motor spool with an adjustable flow control would do what you want. Most hyd. motor set ups don't have a brake when in neutral cause it can be hard to suddenly stop the motor or what it's driving. Do you need it to hold when in neutral? First thing you need to do is figure out how much torque/power your motor needs. A lot of the small motors don't have a lot of power but it depends on the design and what you need to do. I replaced a motor in my skid steer and it cost $1300 just for the motor. The variable displacement pump would cost a lot more than that.

Check the link below for hydraulic transmissions. These units come in different capacities. They use variable displacement piston motors. This is similar in concept to hydrostatic driven tractors. You could also find them in compact tractors and riding lawnmowers.

Many years ago, I made a honey extractor using an integral piston pump and motor on one shaft in one housing. Totally reversible and variable. I'll bet you could find a few on eBay.
Hydraulic transmission

You are way too kind!. Thanks. J.

Where are you in Ohio? I used to work with some people in hydraulics that do this every day. Also like was mentioned equip the system with a flow control like a snow plow/salt spreader spinner control. They are cheap. You could even computer control it!

I have done that on the cheap. I used a two way valve like on a loader and added a water gate valve to act as a restricter after the hydro. valve on the side I wanted speed controll. By operating the hydro valve and turning the water valve at the same time, I had infinate speed controll. Once I got the speed rite, leave that water valve alone.
This was in a lite duty application and worked great.

Memory is hazy...but I think that "BRAND" of
Omaha, makes a flow control directional valve

This may not sound like what you could use but here goes...

What about adapting the Hydrostatic transmission from a Good Riding Mower..??
They (the Cast Iron ones) Last many, many years without any service at all...
The Control Valve and all is there and can be placed anywhere you would like...
You could even delete the "Transmission" and just use the Hydraulic Motor from the Hydrostat trans..along with the Control Valve..
Cheap and they are Complete Units..
Ron..

You can't just use the motor and control valve from the hydrostatic drive. The control valve is part of the hyd. pump and you need the pump and motor to have a hydrostatic drive. Find a golf course equipment distributor and see if they have any old trade in machines like a greens mower or rough mower. They'd be pretty cheap and are run completely by hydraulics.

Plenty Hydrostatic riding mowers have the control valve mounted at a foot petal or Hand control on the Dash..
The Pump is always engine-Driven and the Motor just happens to turn a Gear that in turn drives the rear wheels in Forward and Reverse in infinitely variable speeds..
It is just a Hydraulic Motor with a control valve..
The "transmission" really is just an oil reservoir with the drive gears running in that oil..

Ron.