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Hydraulic pump/motor question
tapwater
Member Posts: 10,336 ✭✭✭
...I have a log splitter that had a small gear type pump on it. One of the gears cracked, and no parts are to be had. I have several hydraulic motors. Can a motor be used as a pump? I don't see why not, as the internals are similar. Anyone know?
Comments
The motor will not create any pressure so will not work. Don
...I'll take your word for it, but why? The pump and motor both have a gear on the shaft and an idler gear. Inlet and outlet ports...I just don't see the difference. A two stage pump is a different animal, but why wouldn't the motor act the same as a single stage pump?
quote:Originally posted by dcon12
The motor will not create any pressure so will not work. Don
...I'll take your word for it, but why? The pump and motor both have a gear on the shaft and an idler gear. Inlet and outlet ports...I just don't see the difference. A two stage pump is a different animal, but why wouldn't the motor act the same as a single stage pump?
A motor needs some head pressure to work, a pump, creates head pressure. Ask someone else what head pressure is. Don
Hydraulic pumps usually drive hydraulic motors such as a hydro drive tractr or zero turn mower. A pump(internal or external) is driven via belt or gear with hoses/lines attached to a wheel motor. The motor can be driven either forward OR reverse. F or R speed is detemined usually by the pump volume having different flow rates in F or R.
Car wash will use an electric motor attached to a hydraulic motor that drives the brushes. Often there may be a gear transmission inbetween as a torque multiplier reducing electrical input needs.
Pump output can be variable displacement which will directly affect motor speed. Motor are most generally fixed displacement.
Now if your hydraulic pump is a single stage (one set of gears) you will benefit greatly by upgrading to a two stage pump (two sets of tandem gears) increasing speed, and power.
Example; 8 hp w/single stage vs.5 HP w/two stage. If pump output is equal, and cylinder is equal the 5 HP will equal the power of the 8 HP, but with a faster piston unloaded travel speed, and take LESS fuel.
If you have fragments, or better yet, the broken gear, there are companies out there that will "reverse engineer" and manufacture you your replacement gear....
...The gears are identical, so I do have an intact one to copy.
...This is a real freak of a splitter. A local company built these to be powered by your chainsaw. Can you imagine splitting wood with a saw at full throttle the whole time? Dumb idea.
...When I got it, it had a 1hp electric motor, since replaced with a 2hp, 3450 rpm motor, belt driving the pump.
...It's an Enerpac pump with integral reservoir. It must have been a special run because I can't find it on the Enerpac website.
...Maybe I'll have to break down and buy a pump and rig a reservoir. Now....How big a pump can I drive with the 2hp, 3450 rpm, 220v motor? It would still be belt driven, so I can change sheaves around to vary the speed.
But on occation, we just put on some fresh material directly onto the gear and reshape the thing.
There's "Mackay Build Up-O" that's good for the job (welding) or there's also some materialt for gas-welding.
It's easy to do - build up of a new tooth on a gear.
Worse thing is, if the gear have cracked from the axle and outwards.
Never tried repairing one of those.
Besides, these gears have very tight tolerances which you are not likely to duplicate.
I think it will work if you remove valving if it exists.
Gear motors can at times. Vane or rotary type pumps cant.
A log splitter works best and cycles faster with a 2 stage pump. They also create the most pressure from small engines like used on log splitters.
A Haldex two stage 11 GPM pump can be gotten from Northern Tool for as little as $120.00.
Which would a heck of a lot cheaper than trying to convince someone to "reverse engineer" a single gear and a lot less down time waiting for that very expensive part to be "custom built" to your specs.