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Sizing a 1to1 90 degree gearbox

Sizing a 1to1 90 degree gearbox

Sizing a 1to1 90 degree gearbox

Good morning, I'm just a high school grad with a hobby. I want to connect a gearbox to a hydrostatic wheel motor. This is on a zero turn mower with 37 HP. Engine so the power is split between 2 drive sides and a 61in mower deck. The hydrogear zt4400 pump/motor boasts capabilities of up to 500 ft pounds torque output. With 24 inch tires this machine will travel approx 13 mph. I want the gearbox to handle the full torque in certain instances. I will use a 1to1 ratio The hp of the motor made sense to me...I need maybe a 30hp gearbox with 1inch shafts. Now I'm thinking because of the torque I'm way off? Look forward to advise and learning. Thanks!

RE: Sizing a 1to1 90 degree gearbox

AGMA publishes papers on gear design.


Tooth bending and contact pressure are the fundamental design constraints.

RE: Sizing a 1to1 90 degree gearbox

Attached is some fairly easy to follow literature on shaft sizing. You should be able to get a feel for whether a 1" shaft will handle 500 lb-ft (6000 lb-in) of torque. Bending will play a factor, as well as the design factors for shock loading. The chart on the last page is a quick way into this.

RE: Sizing a 1to1 90 degree gearbox

Thermal, thermal, thermal. I've seen a drive like this in use in a pharmaceutical production environment. The machine needed to run continuously and it ran to thermal runaway within 20 minutes, loaded or not. Whatever brand of drive it was, it was rated for much lower RPM or strictly intermittent use and the machine builder didn't consider that. It was a chunk of metal with a couple of bearings and a bevel set and no capacity to remove heat. We took out that right angle drive and replaced it with a belt drive.

So yeah, torque capacity is necessary but so is heat.


RE: Sizing a 1to1 90 degree gearbox

Thanks for the responses, As I continue looking into this I'm seeing that i might be into far more $ than originally Hoped for. I will try to post as make more conclusions. Thanks again

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