Drive train effieciency/power loss
Drive train effieciency/power loss
(OP)
I have noticed a common quesion in this forum lately on the effeciency of a gear train. I have a question to add to this. I am designing a drive for a hospital bed. I have my motor at the performance I need (motor only). I am using a transaxle, much like the electric scooters have, and I am wondering what that will do to my eff? My motor is 70% eff. at the .9 HP and output speed that I need.
Once I put this on my transaxle, my eff. will decrease.
My question is this, will the drop in eff. affect my torque or my speed? For example, say i had a 100% eff motor. Once I put it on any gearbox my eff dropped to 75%. Now,do I lose speed or torque or both through the inefficiencies? If i have a 20:1 gear reduction (motor coupled to pinion driving ring gear coupled to shaft) is my speed should be exactly 20 times less, so I should then be losing torque?
What exactly causes a motor with gearbox to be less eff. than a motor only?
Once I put this on my transaxle, my eff. will decrease.
My question is this, will the drop in eff. affect my torque or my speed? For example, say i had a 100% eff motor. Once I put it on any gearbox my eff dropped to 75%. Now,do I lose speed or torque or both through the inefficiencies? If i have a 20:1 gear reduction (motor coupled to pinion driving ring gear coupled to shaft) is my speed should be exactly 20 times less, so I should then be losing torque?
What exactly causes a motor with gearbox to be less eff. than a motor only?
RE: Drive train effieciency/power loss
Edson Campos
edsoncampos@earthlink.net
RE: Drive train effieciency/power loss
Thank you for your reply. I should have added the fact that I am trying to size my motor by calculating backwards through the gearbox.
I know what torque I need at my output to move the load at the customers specifications. I have an electric motor that will do the job. What I am wondering is if I have to redesign my motor to take into account the inefficiency of the gearbox? I know the gearbox is not 100% efficient, so i have to redesign my motor, but do I redesign for speed or torque?
RE: Drive train effieciency/power loss
Edson Campos
edsoncampos@earthlink.net
RE: Drive train effieciency/power loss
RE: Drive train effieciency/power loss
Thank you for your responses, that was what I was looking for. I have heard a rumor that a good estimate for efficiency loss is 10% per gear reduction, does that sound about right? I also saw in a university study that transaxle motors at free speed are about 70% eff. Under load that dropped as low as 45%. I just need to know some general information like that. If anyone has any I would love to hear. Thank you for your help.
Smitty