Figuring Required HP for a DC motor 1

[selmo]

Hello,
I am building a vertical lift system with a rack and gear system. The cart will track along a linear shaft using pillow blocks. The total load is about 100lbs max. I want to use a worm gear and worm so it will self brake. The total distance of travel is 6ft. I would like it to move a 12-18 ft per minute.

Can anyone tell me what HP or torque is needed to make this system work? I am thinking about using a dc motor.

Also, I was considering connecting the worm gear directly on the rack as well as to the worm. As long as the pitch and presure angle are the same this should be okay right?

James Kearns

 

[Philrock]

1 h.p. = 33,000 ft-lbs/min.
You have 100 lbs * 18 ft/min = 1,800 ft-lbs/min. = 0.055 h.p.
Worm gears are somewhat inefficient, say 65%.
0.055/0.65 = 0.084 h.p. or about 1/12 h.p. Be conservative and use a 1/6 or 1/4 h.p. motor. At the low end of your speed range, you could get away with 1/10 h.p.

Safety codes do not consider worm gears to be non-backdriveable - i.e. if safety is an issue, don't count on the worm gears to be self braking.

A worm will not mesh properly with a rack.

 

[selmo]

Thank you very much Philrock. That is exactly what i needed.

Safety is not a hugh concern, however what would you recommed using?


James Kearns

 

[Philrock]

There is a wide variety of motors available with built-in brakes, though the selection is not as good with d.c. as it is with a.c. Graingers sells many motors with brakes. These are sometimes referred to as brakemotors. Also, Horton, Warner, and others make brakes that sandwich in between the motor and the gearbox. For more possibilities, try

http://www.thomasregister.com.