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High Torque, Large Gear reduction gearbox

High Torque, Large Gear reduction gearbox

High Torque, Large Gear reduction gearbox

Hello Everyone

I'm a long time reader, first time poster to Eng-Tips.

I'm looking for a gearbox for an application we have which involves lifting/rotating a heavy piece of machinery on transportation device. I'm not entirely sure something like this is possible or, at the very least, feasible for this application.

The gearbox shall be hand operated via handwheel or similar device.
The torque values will be around 50,000 N-m (37,000 ft-lbs)
Based on this value and the calculated input torque, the gear reduction will need to be ~10,000:1.
The output shaft only has to rotate a total of 90 degrees (horizontal to vertical) and must be bi-directional.

Can anyone recommend a starting point for me?

Much appreciated.

RE: High Torque, Large Gear reduction gearbox

Take the last stage of reduction with a roller chain, a big bull sprocket and a small drive sprocket.
That should be you into a range where ordinary gear reducers become affordable.

Mike Halloran
Pembroke Pines, FL, USA

RE: High Torque, Large Gear reduction gearbox

If the reducer is to be hand-cranked, my first recommendation is for endurance work on your arm strength.

10,000:1 for 90 degrees equals 2,500 rotations on the input shaft. If you could maintain one revolution per second at the input shaft that would be 2,500 seconds, or about 42 minutes. If you are paying someone very much of a wage, you can avoid the labor costs by installing a small motor.

You are probably not going to throw any lubricant with a hand-cranked reducer, so it will require special lubrication.

RE: High Torque, Large Gear reduction gearbox

It's about 1.1 HP-minute to get 37000 ft-lbf. If it's pedaled that would be an easily produced .1 hp for 11 minutes; figure considerable friction losses and maybe the rider is a bit more strained or it takes longer. Hand cranking will take a lot longer.

I'd look at using a hydraulic motor and bike mounted pump. As required, it would be easy to drive the pump some other way, like a small gas motor or mechanical pickoff. Reverse the direction with a hydraulic valve and no change in input direction is required.

RE: High Torque, Large Gear reduction gearbox

If you go hydraulic, the gearbox can be simplified or eliminated completely.

je suis charlie

RE: High Torque, Large Gear reduction gearbox

A 10,000:1 gear drive would have miserable efficiency. In fact, unless you were very careful about how you designed the gear drive it might have enough internal mechanical losses that you would not be able to operate the system by hand.

RE: High Torque, Large Gear reduction gearbox

Subject to travel etc, maybe a hand operated hydraulic power pack/cylinder/lever(s) is an option.


RE: High Torque, Large Gear reduction gearbox

Thank you all for your replies. The current system uses hydraulic cylinders to raise/lower the frame. We are trying to reduce cost by looking at alternative actuators, but it's starting to look as though the hydraulic system is in fact the most cost effective.

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