the 'todays job' thread

[AHPP]

Is it a hydraulic motor and then some

planetary gears like a truck bumper winch?

[Mick Dempsey]

If I’m honest I have no idea what goes on in there.

Clearly the Hydraulic motor turns something. 
What’s happening inside the drum is unknown to me.

[sime42]

It's a Black Box operation in fact.

 

 

[Mick Dempsey]

Thinking about it, it can’t be as simple as a turning a shaft inside the drum to turn the unit (in the same way as a motor turns a feed roller on a chipper) because that couldn’t generate the force that the drum produces.

[GarethM]

Doubt it has a reduction planetary gearbox, just relying on pure low capacity hydraulic grunt from pressure at 210-300 bar.

 

There's a calculator somewhere, plus it depends if it's a standard pump or a piston type.

 

Two hoses are in & out, smaller is just case drain back to the tank.

 

You'd be surprised how simple a lift assist cylinder is on a tractor, but two of those is 3-6 ton depending on model.

[Mick Dempsey]

13 minutes ago, GarethM said:

Doubt it has a reduction planetary gearbox, just relying on pure low capacity hydraulic grunt from pressure at 210-300 bar.

 

There's a calculator somewhere, plus it depends if it's a standard pump or a piston type.

 

Two hoses are in & out, smaller is just case drain back to the tank.

 

You'd be surprised how simple a lift assist cylinder is on a tractor, but two of those is 3-6 ton depending on model.

Then why the creep if the motor is replaced?

Even if the hydraulics are disconnected. 

Edited November 5 by Mick Dempsey

[GarethM]

Just now, Mick Dempsey said:

Then why the creep if the motor is replaced?

Even if the hydraulics are disconnected. 

Case drain I guess, plus hydraulics pumps don't form a complete seal internally and does bypass ever so slightly so always expect a little movement.

 

The big boy forestry ones a think have a clutch setup to prevent that creep.

[openspaceman]

4 minutes ago, Mick Dempsey said:

Then why the creep if the motor is replaced?

Even if the hydraulics are disconnected. 

There will always be creep as some oil from the high pressure side seeps past the spool valve or to that drain line on the motor. On track motors a brake is applied if there is no pressure being sent to the motor.

 

If it is leaking past the spool valve you could fit a check valve in the supply to the winch.

[AHPP]

What’s the brake on a track motor? I always assumed it was a check valve. 

[Mick Dempsey]

3 minutes ago, openspaceman said:

There will always be creep as some oil from the high pressure side seeps past the spool valve or to that drain line on the motor. On track motors a brake is applied if there is no pressure being sent to the motor.

 

If it is leaking past the spool valve you could fit a check valve in the supply to the winch.

Thanks, the spool valve is out of the equation, as I said, you can disconnect the hydraulics and the creep continues till it’s ‘happy’ with the pressure.