Gruber
HobbyMasters
M.L. Toys
KidsWheels
Gruber
HobbyMasters
M.L. Toys
KidsWheels
HobbyMasters M.L. Toys
Gruber
KidsWheels
Need new motors? Grind a gearbox? Adding teeth to a pinion?
User avatar
By Dvanman
#147338
The Little tykes 442S Hummer we found in the trash seems to work fine at high speed but at low speed and reverse the left wheel runs at half the speed of the right wheel. Voltage measured across both of the motors is 12vdc at high speed. At low speed the "good" right motor measures 6v but the "gimpy" left motor starts at 6v and quickly drifts down to 2 or 3v. First actions was to disassemble the switches and clean all the contacts. Next I swapped the leads of the two motors but the problem stayed with the left motor. That indicates a problem in the left motor.
Before I start looking for a replacement motor, is there any way to fix this old one???
User avatar
By wired
#147339
If they both run fine in high speed then I wouldn't suspect a bad motor. When in low or reverse the motors run in series. Any amount of drag or resistance will cause power to transfer to the side of least resistance. You can simulate this by lifting the vehicle off of the ground and grabbing one of the rear wheels. The wheel you grab will stop and the other wheel will continue to spin but a little faster. If there is a bent axle or any binding one one side of the rear wheel you will see a difference in both voltage drop and amperage draw. Look for anything wrapped around the axle (string etc...), a bent axle or it may just be a gearbox with a little more natural drag. I'm not saying one motor may not be stronger (or weaker) than the other because they do wear over time, but if they work fine in high speed then what you are experiencing may be absolutely normal. Is there a performance issue when driven in low or reverse?
User avatar
By Dvanman
#147340
My testing is with both real wheels off the ground. I can actually stop the slow wheel by putting my hand on it when the shifter is set to the lower speed. With no power applied, it takes about the same effort to spin the wheels manually. I don't hear any unusual sound or see any indication of bent axle.
User avatar
By wired
#147341
Sounds normal to me. Since it's a series circuit in low/reverse you can expect there to be some difference in wheel speed in a no-load condition (wheels off the ground). Most real vehicles perform in the same manner. The wheel with least resistance will spin while the other remains static. If it's driving fine I wouldn't suspect any problem with a motor.
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