DaveAK

03 February 2011, 1658

After I finish my bike I have a new project for the summer months. It will be a small tracked vehicle, so I'm looking for two motors. It's going to be slow speed, but needs a lot of torque. It will be run at 24-48V depending on motors. Taking a look at a couple of offerings I'm just not getting how to make a reasonable decision.

Compare these for me:

D&D SepEx as used by Tony: http://www.evdrives.com/dd_motors_170-512-0005.html

This D&D 512:5 is a Brush-Type, Shunt motor Capable of 2.2 KW continuous and 15 KW for 1 minute.

•24 - 72 VDC

•7/8" single-shaft base/face-mounted

•6.7" Dia x 8.5" Long

•Actual Weight 38 lbs

•Shipping Weight 43 lbs

CONTINUOUS RATING: @ 48 Volts

•3100 rpm

•2.8 ft lbs torque

•45 amps armature

•9.5 amps field

•2.3 HP

PEAK RATING:

•4500 rpm

•14.3 ft lbs torque

•350 amps armature

•20 amps field

•8.5HP

eBay offering: http://cgi.ebay.com/4-HP-24V-DC-VEHICLE-ELECTRIC-MOTOR-/230415376902?pt=LH_DefaultDomain_0&hash=item35a5d3a206

4 HP 24 VDC ELECTRIC MOTOR

45 AMPS NO LOAD

140 AMPS FULL LOAD

8000 RPM FULL LOAD

32 INCH POUND OF TORQUE

¾” DIAM. X 1 ¾” SHAFT WITH KEYWAY

MOTOR DIMENSION 4” DIAM. X 7 ¾”

SHPG 24 LB (ESTIMATED)

The eBay one has 4HP @ 24V vs. 2.3HP @ 48V. It has similar torque, but spins a lot faster. I would have to gear it down a lot more, so what effect would that have on torque? (I used to know this stuff.) Apart from the speed I feel it better suits my application, but I'm curious as to why it has more HP at a lower voltage.

How do you choose a motor for high torque and low speed?

Compare these for me:

D&D SepEx as used by Tony: http://www.evdrives.com/dd_motors_170-512-0005.html

This D&D 512:5 is a Brush-Type, Shunt motor Capable of 2.2 KW continuous and 15 KW for 1 minute.

•24 - 72 VDC

•7/8" single-shaft base/face-mounted

•6.7" Dia x 8.5" Long

•Actual Weight 38 lbs

•Shipping Weight 43 lbs

CONTINUOUS RATING: @ 48 Volts

•3100 rpm

•2.8 ft lbs torque

•45 amps armature

•9.5 amps field

•2.3 HP

PEAK RATING:

•4500 rpm

•14.3 ft lbs torque

•350 amps armature

•20 amps field

•8.5HP

eBay offering: http://cgi.ebay.com/4-HP-24V-DC-VEHICLE-ELECTRIC-MOTOR-/230415376902?pt=LH_DefaultDomain_0&hash=item35a5d3a206

4 HP 24 VDC ELECTRIC MOTOR

45 AMPS NO LOAD

140 AMPS FULL LOAD

8000 RPM FULL LOAD

32 INCH POUND OF TORQUE

¾” DIAM. X 1 ¾” SHAFT WITH KEYWAY

MOTOR DIMENSION 4” DIAM. X 7 ¾”

SHPG 24 LB (ESTIMATED)

The eBay one has 4HP @ 24V vs. 2.3HP @ 48V. It has similar torque, but spins a lot faster. I would have to gear it down a lot more, so what effect would that have on torque? (I used to know this stuff.) Apart from the speed I feel it better suits my application, but I'm curious as to why it has more HP at a lower voltage.

How do you choose a motor for high torque and low speed?