hydraulics help

[jdog_kustoms 82]

i am looking to make a crawler out of a wheel horse tractor i am gona use a gt1100 carcass and a 10 hp diesel engine turned a 1/4 turn from normal so its like a d series engine but instead of the normal 8 speed or 4 speed rear with turning brakes i would like to make it hydrostatic i was looking at using parts of an old wheel horse zero turn but the eaton 7`s are the weak spot so my quaetion is does anyone have any idea displacement and psi i need to run if i just get a pump to run off the engine and use 2 hydraulic motors sorta like a bobcat does and im gona run a second pump off the engine for remote onboard hydros for any attachment i put on it any help or ideas would be good even if you thinkthis is a dumb idea just klet me know im still in the creation part of this and i am new to all the hydraulic stuff

[SousaKerry 502]

No clue on that one but our friend on here that builds the 4X4 articulated machines would prolly know better then anyone else. Anyone here got his contact info? His name escapes me at the moment

[Martin 2,133]

That would be Bob Rock.....

Whlpny I think is his username.

Edited December 31, 2012 by Martin

[smoreau 658]

First of all you will need to find out how fast you want it to go. That will give you your wheel speed then do you want to gear reduction the motors? That Can make a small motor do a lot more. Once you have your motors figured out, you can see what size pump to go with. You can also use a 2 in 1 pump to operate your hydraulics. That would simplify your setup. I would look at hydro-gear for there hydrostatic pumps that operate a hydraulic motor like a professional zero turn mower. They can make them to your spec. For around $500 each. This would simplify your controls greatly. Just some things to think about.

[castoff 6]

To build a crawler, you need to emulate the drive train used on skid steer loaders and also on ZTR's. Each track must be fully independent so that you can steer the crawler. Originally, this was done with mechanical steering clutches that interrupted the power going to one track. With the advent of improved hydraulic components, the aforementioned machines use dedicated hydrostatic pumps to deliver oil to each hydraulic motor that drives one of the tracks.

A hydrostatic pump is a totally different design than a standard hydraulic pump.

The hydro pump in combination with the motor it serves is essentially a closed system. Inside the hydro pump is a device called a "swash plate" that resembles the butterfly plate in a carb. The operator of the machine controls the swash plate with either his hand or his foot. When the swash plate is dead vertical inside the pump, no oil leaves. When the operator tilts the swash plate one way or the other, then oil leaves one of two ports in the pump. Both ports are connected directly to the ports on one of the drive motors. If oil leaves the left side of the pump, then the motor will rotate clockwise. If the swash plate is tilted the other way, then oil leaves the right side of the pump and the motor rotates counter-clockwise. Oil leaving the motor is returned to the opposite side of the pump so it can become available for the pump to deliver more oil to the motor.

Speed of the motor is controlled by how much the swash plate is tilted just like engine speed is controlled by how far the throttle plate is tilted. There is no need for me to explain what the swash plate does. What matters here is that you understand that you need to use individual hydrostatic pumps for this project along with separate drive motors.

As smoreau pointed out, there are hydrostatic pumps that can be put in tandem, meaning that the internal combustion engine of choice is used to spin the first pump directly off of it's crankshaft stub by using a LoveJoy style connector along with a pump mounting bracket that bolts to the rear of the engine and also provides a mounting surface for the first pump. A second pump is then bolted behind the first pump thanks to a removable plate on the first pump that exposes a female drive shaft. It is also possible to mount a third pump this way. The third pump would be of the common gear type fixed displacement variety to operate hydraulic cylinders such as those on a dozer with a 6 way blade or on a crawler with a loader attachment.

You have to decide whether your project is to be a "yard ornament" that can be driven around but lacks the power needed to perform real work or a fully functional machine. If all you want is a yard ornament, then pumps and motors from a ZTR will do the trick. Keep in mind that an engineer has already done his homework to match the pumps and motors to each other and to the task of powering a ZTR on rubber tires. If you want a machine that will truly push dirt, then you have to look at existing machinery that already does that task. The first thing that comes to my mind is the Mini-Excavators. All of these have dozer blades on them for backfilling and levelling trenches they dug with their backhoe attachment. The also have complete track drive assemblies. Another option would be the small chain trenchers that are track driven.

Other than that, I can't think of anything else out there that could be cannibalized for the track drives, motors, pumps and engine. And speaking of engines, you may as well know up front that engine choice will be crucial because it takes HP to drive hydraulic pumps and the more pumps you have, the more HP you need. In addition, the pumps must be sized to the governed speed of the engine you select. Each pump is designed to work at a maximum RPM. It is fine to operate a pump with a max rating of 4000 RPM on a motor that is governed at 3600 RPM but if you install a pump with a max rating of 2000 RPM on that same gas engine, then you will destroy it. I don't know what your budget is for this project but the world of hydraulics is not for those with shallow pockets.

You are going to need a reservoir tank, quite a few hoses and possibly an oil cooler to keep the heat under control.

As for Whipny, he uses Case garden tractor trans-axles along with Case GT pumps, control valves, tanks and coolers for his projects. But he builds articulated tractors with rubber tires. However......I suppose that it would be possible to come up with a hybrid system to accomplish your project.

You could find a low cost Big Wheel Case 444. This would give you a 14 HP K321 Kohler K engine along with the pump and pump mount. It would also give you an oil cooler, reservoir and control valve plus the 2 speed trans-axle with drive motor.

All of this would be the hydraulic side of the hybrid.

Then, you would have to find a pair of automobile disc brake rotors that either matched the 6 on 6 bolt pattern used by Case or could be re-drilled to match. Each rotor would need a hydraulic calliper along with s master cylinder to operate it. You would have to engineer a mounting bracket to secure the callipers to the trans-axle housing. A sprocket could then be spaced away from the rotor on each side and that sprocket could drive a #50 chain that would go to another chain sprocket that was fixed to the same shaft that the crawler track drive sprocket was on. The master cylinders could be controlled by either a foot pedal on either side of the operator's station or by hand levers that the operator would pull toward himself to cause one of the track drive sprockets to slow or stop. The track drive sprocket on the opposite side would speed up thanks to the differential gears inside the trans-axle. Ground speed would be controlled by the Case hydraulic control valve that sends oil to the drive motor. The more you open that valve, the faster the crawler would move. The same valve will give you reverse gear just by pulling the lever toward you from the neutral position. In addition, the trans-axle has a Hi and Low range selector that would provide both a working range and a travel range.

Should you wish to add a one-way dozer blade, that valve has a second spool in it that could operate one or two lift cylinders to raise/lower the blade.

Those are my thoughts on the issue.

[meadowfield 2,616]

The easier cheat I have looked into - at length, is to use a tracked dumper chassis. These are walk behind tracked machines with engine, pump, motors, valves - everything needed to make a tracked machine.

Chris Sutton built one a few years ago and it goes round the shows in the UK.

mark

[castoff 6]

The easier cheat I have looked into - at length, is to use a tracked dumper chassis. These are walk behind tracked machines with engine, pump, motors, valves - everything needed to make a tracked machine.

Chris Sutton built one a few years ago and it goes round the shows in the UK.

mark

While those are common in the UK due to how difficult access is in villages, towns and cities, they are far less common on this side of the pond. I am not saying that the OP should not take your suggestion to heart but rather that I think finding one of those will be difficult and finding one for a cheap price will be next to impossible. Just my opinion.