Hydraulic Motor Help

[darren_nh]

I am building a firewood conveyor (or elevator for you purists). It will by driven from the top with a hydraulic motor. My question is simple (I think). Is the return port on the motor going to "high pressure", or will there be enough loss in the motor to use low pressure connections and install a low pressure return line filter in the line?

Thank you for any help you can provide.

 

[Steve NW WI]

High pressure. The spikes alone when closing the valve are enough to blow out low pressure stuff. For this reason, you should use a valve with a float position to let the motor coast to a stop.

Also, should something go wrong and jam the conveyor, it's nice to be able to pull the lever the other way and have reverse.

Although I get the concept of running a top drive, farm elevators have worked well for a long time with bottom drive. Easier to work on, and cheaper.

 

[nathon918]

usually you run the motor work ports through the spool work ports and return through the spool that way you can run either direction... are you controlling it with a spool or just pump output directly to the motor? i dont really see why you couldnt just power one side of the motor and have the other side to the return. personally id controll it with a spool plumbed to both sides of the motor incase i ever need to to run backwards...

 

[jags]

It can be run with a low pressure return, but as said above, it would sure be nice to have the ability to hit reverse if need be.

Will you be using an aux. pump? Running from the splitter pump could/would be a pain.

 

[nathon918]

High pressure. The spikes alone when closing the valve are enough to blow out low pressure stuff. For this reason, you should use a valve with a float position to let the motor coast to a stop.

Also, should something go wrong and jam the conveyor, it's nice to be able to pull the lever the other way and have reverse.

Although I get the concept of running a top drive, farm elevators have worked well for a long time with bottom drive. Easier to work on, and cheaper.

most actual "firewood conveyors" (chain type) have the hydraulic motor at the top that way you arent "bunching up" the chain at the bottom if theres any slack in it.
and you are right farm/hay elevators work perfectly fine with a bottom drive, cause who the hell wants to have to lift the conveyor and the motor up into a barn, i like the heavy end on the ground...:cool2:

 

[darren_nh]

High pressure. The spikes alone when closing the valve are enough to blow out low pressure stuff. For this reason, you should use a valve with a float position to let the motor coast to a stop.

Also, should something go wrong and jam the conveyor, it's nice to be able to pull the lever the other way and have reverse.

Although I get the concept of running a top drive, farm elevators have worked well for a long time with bottom drive. Easier to work on, and cheaper.

No valves were planned, but plans change. The motor is already mounted at the top as sometime pushing a chain can be difficult. i can lower the unit to an easier working height.

The pump on the engine was going to be plumbed directly to the motor.

Thanks for the quick response.

 

[darren_nh]

It can be run with a low pressure return, but as said above, it would sure be nice to have the ability to hit reverse if need be.

Will you be using an aux. pump? Running from the splitter pump could/would be a pain.

It has its own pump on a 5hp honda.

 

[turbo885]

High pressure. The spikes alone when closing the valve are enough to blow out low pressure stuff. For this reason, you should use a valve with a float position to let the motor coast to a stop.

Also, should something go wrong and jam the conveyor, it's nice to be able to pull the lever the other way and have reverse.

Although I get the concept of running a top drive, farm elevators have worked well for a long time with bottom drive. Easier to work on, and cheaper.

Conveyors really dont work well with bottom drive they slip the drive needs to be at the top. Hay elevators are cog driven chain so no slip

 

[darren_nh]

It can be run with a low pressure return, but as said above, it would sure be nice to have the ability to hit reverse if need be.

Will you be using an aux. pump? Running from the splitter pump could/would be a pain.

So "typically" enough pressure is lost in the motor, that the return port could be plumbed with a low pressure return line filter?

 

[jags]

So "typically" enough pressure is lost in the motor, that the return port could be plumbed with a low pressure return line filter?

To think of it in a different manner - it is not really lost pressure, but the lack of a restriction (such as a motor or cylinder/valve.)

As a side note: why not run the elevator with the honda and forget about the hydraulics?

 

[Deereman76]

If the outflow side of the motor is straight back to the resevoir, with no valves, no quick disconects that can pop apart, then yes, Low pressure stuff can be used. If you are returning the oil through a Control valve, Then there is a chance of reversing the system, then I would run pressure hoses both ways.

Old Hay elevators were bottom drive so they could be driven by a tractor PTO....

 

[darren_nh]

To think of it in a different manner - it is not really lost pressure, but the lack of a restriction (such as a motor or cylinder/valve.)

As a side note: why not run the elevator with the honda and forget about the hydraulics?

1. Hydraulics are more fun.
2. Don't have to figure a gigantic flywheels size to reduce the ratio.
3. Don't have to buy a gear box to reduce the ratio (see #2.) (Probably would have saved money).
4. Wanted to try a "different" design.
5. Didn't want to deal with slipping belts.

 

[darren_nh]

If the outflow side of the motor is straight back to the resevoir, with no valves, no quick disconects that can pop apart, then yes, Low pressure stuff can be used. If you are returning the oil through a Control valve, Then there is a chance of reversing the system, then I would run pressure hoses both ways.

Old Hay elevators were bottom drive so they could be driven by a tractor PTO....

Was not planning on a reverse valve, and only a return line filter coming from the motor.

 

[nathon918]

the only problem i see is its probably going to be hard to start the engine since its always going to be under pressure, with an open center spool the no pressure buildup since it just runs straight through the spool and back into the tank.... you could probably plumb some sort of by-pass valve so it just dumps into the return instead of through the motor while your starting the engine, then close the by-pass valve to power the motor. the by-pass would have to be rated for pressure atleast to the valve, may be something to think about...

 

[darren_nh]

the only problem i see is its probably going to be hard to start the engine since its always going to be under pressure, with an open center spool the no pressure buildup since it just runs straight through the spool and back into the tank.... you could probably plumb some sort of by-pass valve so it just dumps into the return instead of through the motor while your starting the engine, then close the by-pass valve to power the motor. the by-pass would have to be rated for pressure atleast to the valve, may be something to think about...

I don't agree. The pump mounted to the engine will draw from a vented tank with no pressure. The engine should not be hard to start. The pump will drive the motor (at the top of the elevator) and return the fluid to the tank.

 

[nathon918]

I don't agree. The pump mounted to the engine will draw from a vented tank with no pressure. The engine should not be hard to start. The pump will drive the motor (at the top of the elevator) and return the fluid to the tank.

when you turn over or try to start the engine you are spinning the pump which builds pressure, which makes the pump and engine harder to turn...

 

[Butch(OH)]

Hi Darren, As long as you dont use a valve and start and stop the elevator with the engine you can use low pressure hose from the motor back to the tank. There is only pressure in the system between the pump and the work. Steel hydraulic tubing is not very expensive you might want to check it out prior to using hoses for either the feed or return lines. I have a bit of experience with various elevators and firewood and I think your going to end up with a valve at some point if for no other reason you have no pressure relief if you dont. With a valve not only can you set the pressure down so that when it gets bound up(and it will) it will simply stop instead of breaking something you can also reverse it to relive the stoppage and go again. Starting the engine with no valve will be OK in warm weather and noting on the elevator (no load equals no or little pressure) but when it gets cold out just moving the oil through a long line makes resistance and resistance is what makes pressure and pressure is what takes power. Anyway its not hard to add a valve in the system in afterthought should you decide you need one. You will of course have to replace the low pressure return line unless the valve only provides one way operation.
Good luck with it, Butch

 

[darren_nh]

Hi Darren, As long as you dont use a valve and start and stop the elevator with the engine you can use low pressure hose from the motor back to the tank. There is only pressure in the system between the pump and the work. Steel hydraulic tubing is not very expensive you might want to check it out prior to using hoses for either the feed or return lines. I have a bit of experience with various elevators and firewood and I think your going to end up with a valve at some point if for no other reason you have no pressure relief if you dont. With a valve not only can you set the pressure down so that when it gets bound up(and it will) it will simply stop instead of breaking something you can also reverse it to relive the stoppage and go again. Starting the engine with no valve will be OK in warm weather and noting on the elevator (no load equals no or little pressure) but when it gets cold out just moving the oil through a long line makes resistance and resistance is what makes pressure and pressure is what takes power. Anyway its not hard to add a valve in the system in afterthought should you decide you need one. You will of course have to replace the low pressure return line unless the valve only provides one way operation.
Good luck with it, Butch

Is a valve like this: Surplus Center - 1/2 NPT HYD FLOW CONTROL VALVE W/RELIEF RDRS150-16

what is needed to reverse the direction of flow? I will need to also buy a suction filter instead of return filter if I go this route I would imagine.

 

[Butch(OH)]

Nope, you need a valve like the ones used on splitters except the make them special for motors so they will coast when in in neutral.

This is a motor valve that also has flow control so you can run the conveyor either way plus control the speed independently of the engine speed. Surplus Center - 1 SPOOL 18 GPM MOTOR VALVE W/ FLOW CONTROL

This is same type valve with no flow control Surplus Center - 1 SPOOL 8 GPM PRINCE MB11C5C1 MOTOR SPOOL VALVE

Actually since you have smallish inertia loads to deal with you could use just about any open center two way valve as long as it has a detent in at least one direction to hold it open. The special motor valves are used when running equipment that has a large flywheel affect. they allow the equipment to coast to a stop.

You should stick with the return filter I think. Just make sure the tank and lines are reasonably clean when you install them. The suction filters are expensive and always used with a return filter, or should be as they offer much larger,,coarser?? protection meaning bigger debris can pass through them. The return line filters will take out smaller particles. This reasons for all this filtering complication is pumps dont like hard draws but like to push. You dont want heavy restriction on the intake side.

 

[nathon918]

Is a valve like this: Surplus Center - 1/2 NPT HYD FLOW CONTROL VALVE W/RELIEF RDRS150-16

what is needed to reverse the direction of flow? I will need to also buy a suction filter instead of return filter if I go this route I would imagine.

thats a flow controller, (controls motor speed) you need something like this Surplus Center - 1 SPOOL 20 GPM PRINCE RD-2575-M4-EDA1 MOTOR VALVE
you have an inlet port (from pump) then your work ports (connects to motor) and a return port, id stay away from a suction filter, if its clogged or doesnt flow enough it will cause the pump to cavitate (starve the pump of oil) ruining the pump...