Hello, I have a case 1840, I am interested in the required pressure in the tandem pump and I am also interested in the oil flow rate. I bought a Case at auction and when it arrived it arrived without a pump. I would put in 2 gear pumps so I'm wondering what the oil flow is and what the pressure is?
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Skid steer Case 1840 tandem Pump hidraulic problem
- Thread starter Aleks123
- Start date
Kyle Helmke
Well-Known Member
they cannot be gear pumps they are variable displacement pumps for the travel motors the aux pump i think is gear
Welder Dave
Senior Member
Yes, you a need tandem variable displacement hydrostatic pump with an aux. pump on the front to power the hyd's. The tandem pumps are matched to the drive motors. The aux. pump is generally a gear pump. Hopefully you didn't pay much for the machine. A tandem hydrostat pump is quite pricey. You'd want to make sure the hyd. reservoir and the rest of the hyd's. are perfectly clean before hooking up new pumps.
Well, you see, I'm from Serbia and I haven't found a pump anywhere, only in Mexico, which is very far from me... I would insert 2 gear pumps. Each one would have all the distributor from where I would control them and I hope I would get that she is a cougar. It's not a problem to me, and if the pump is weaker, it's not a problem, it's better that it works somehow than not at all... But I'm interested in the pressure on the pump and the oil flow
Welder Dave
Senior Member
You would have no control with gear pumps and no power. I think the hydrostatic pumps in my skid steer are 3700 PSI but some are as high as 5500 PSI. As far as I know, gear pumps are generally below 3000 PSI.
Further to Vetech's post, you would be constantly stalling the machine. Gear pumps wouldn't provide any load sensing that variable displacement pumps automatically provide. Variable pumps give you time to adjust your speed. With gear pumps you'd have to stop and start the flow when doing any kind of digging or loading. There would be no way to have the infinitely variable speed that's required for a skid steer.
There are hyd. drives that could use gear pumps but they wouldn't work on a skid steer. Early golf course greens mowers used a simple pump and motor drive. They were 2 speed, 1 for work and 1 for transport. In work mode you ran full throttle but in transport you could set the throttle for the terrain you were driving on. The difference from a skid steer is a greens mower is a constant speed in work mode with a constant load. The engine governor can control slight differences in load. A skid steer can have huge variances in load and the speed required. Greens mowers went to full hydrostatic drive in the 80's with a foot pedal to control speed. They were better because the operator could easily adjust speed and stop quick if required. Operator still had to drive at a consistent speed when cutting or the greens would be inconsistent. It can be visibly noticeable in some cases. You don't want to pi$$ off golfers, especially members of private clubs. They pay a lot of money and can be worse than the most horrible customer. Superintendents have been fired because of golfers complaints. Jack Nickolaus had a superintendent fired because he made a bad shot and his ball landed beside a sprinkler. The grass was slightly longer around the pop up sprinkler head. It's impossible to prevent the longer grass. You'd have to go to every sprinkler with some kind of scissors and trim the grass by hand everytime after the sprinkler shut off. You mess up a green and there'd be a war started. LoL
Further to Vetech's post, you would be constantly stalling the machine. Gear pumps wouldn't provide any load sensing that variable displacement pumps automatically provide. Variable pumps give you time to adjust your speed. With gear pumps you'd have to stop and start the flow when doing any kind of digging or loading. There would be no way to have the infinitely variable speed that's required for a skid steer.
There are hyd. drives that could use gear pumps but they wouldn't work on a skid steer. Early golf course greens mowers used a simple pump and motor drive. They were 2 speed, 1 for work and 1 for transport. In work mode you ran full throttle but in transport you could set the throttle for the terrain you were driving on. The difference from a skid steer is a greens mower is a constant speed in work mode with a constant load. The engine governor can control slight differences in load. A skid steer can have huge variances in load and the speed required. Greens mowers went to full hydrostatic drive in the 80's with a foot pedal to control speed. They were better because the operator could easily adjust speed and stop quick if required. Operator still had to drive at a consistent speed when cutting or the greens would be inconsistent. It can be visibly noticeable in some cases. You don't want to pi$$ off golfers, especially members of private clubs. They pay a lot of money and can be worse than the most horrible customer. Superintendents have been fired because of golfers complaints. Jack Nickolaus had a superintendent fired because he made a bad shot and his ball landed beside a sprinkler. The grass was slightly longer around the pop up sprinkler head. It's impossible to prevent the longer grass. You'd have to go to every sprinkler with some kind of scissors and trim the grass by hand everytime after the sprinkler shut off. You mess up a green and there'd be a war started. LoL
Try 30 GPM @ 4500 PSI
Welder Dave
Senior Member
Yeah, the OP is wasting his time and money if he's trying to run a skid steer with basic gear pumps.
Welder Dave
Senior Member
You can't just replace the tandem hydrostat pumps with gear pumps. It won't work. If you have the original tandem pump, see if it's worth rebuilding. If you don't have it, look for a used one in a salvage yard that could be gone through.
apetad
Senior Member
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This guy is going to end up with the situation as soon as you start the engine BOTH sides are going to go full speed and full speed only, in a straight line and crashing through or killing anyone in it's path!
Welder Dave
Senior Member
I would think he'd at least have control valves but his gear pump idea won't work.