I am not sure if these motors are keepers yet. Well, I will keep them but not sure if they will get installed in this project. The specifications seem good (see below) but the motors, well… they seem so small. I did find some two inch diameter motors but I don’t think they are as plentiful as these Johnson brand motors. The price for the two Johnson’s was about $7.00 each. I have seen a conflicting price on the larger motors but all I see now is about $10.00. At that price it is worth experimenting .
I purchased these Johnson 9167AK from a seller on Ebay. There are quite a few sellers with this motor so it must be widely available. I didn’t see it listed under this number on the Johnson Motor web site. I assume it may be some kind of overstock for someone needing a small motor of these specification.
Johnson Electric 12VDC Motor (6 to 18V) – Model 9167AK
Extreme Torque of 2.2 in-lbs
Super Grip Serrated Shaft
This motor is quite a bit larger than most hobby types. It’s suitable for any model or experimental use where high shaft power and torque are needed. Please note that there are a couple of different Johnson model 9167 motors. The 9167AK is the biggest one with the highest power.
Runs very smoothly over the range of 3VDC to 18VDC.
Light load Medium Load Heavy Load
3VDC: 1,400 RPM 850 RPM n/a
6VDC: 3,150 RPM 2,100 RPM 750 RPM
12VDC: 6,560 RPM 4,900 RPM 3,400 RPM
18VDC: 9,800 RPM 7,350 RPM 5,100 RPM
At 12VDC the motor has very impressive torque.
Starting torque is 2570 gm-cm = 36 oz-in = 2.2 inch-pounds, at 14 amps.
Operating torque at medium load is 440 gm-cm = 6.1 oz-in at 2.8 amps.
As the load is increased, the torque and current will increase correspondingly. Please check that the case temperature stays below about 100 deg C, in order to maintain long life.
On a dynamometer, the motor was able to generate a continuous 31 watts of mechanical shaft power, with a peak value of 46 watts (temperature limited). A typical small hobby motor can only produce 2-3 watts and a medium-size motor about 10-12 watts, usually not continuously.
Overall length is 3-1/2″ including terminals and shaft.
The body is 2-5/8″ long, 1-1/2″ diameter. Or 65 mm by 38 mm if you prefer metric.
The shaft is 3/4″ long. It’s 1/8″ (.125″) dia with a .130″ serrated end section that grips tightly to a suitable hub, pulley or shaft coupler.
The heavy duty self-aligning front and rear bearings are lifetime lubricated oilite bronze.
The brushes are low-friction and long-life graphite carbon, NOT just copper spring arms as in many small motors.
The armature is 5 pole and the spin is reversible by reversing the power wires.