Motor Kit Assembly
Created on: 9 August 2012
A multi-ratio reduction gearbox with electric motor kit is unpacked and assembled as shown in the video. The kit is from Como Drills (part number 917D) and was bought from RS Components (order code 238-9642).
The small electric motor operates from 1.5V to 3V d.c.
How the Reduction Gearbox Works
Firstly, the two orange gearwheels fit tightly to the shafts that have been tapped into them. When an orange gearwheel is turned, the shaft turns with it. The green gearwheels rotate freely on the shaft. The more gearwheels that are added to the gearbox, the slower the output shaft will turn.
If there is one green gearwheel per shaft, then the motor will drive the first green gearwheel which rotates on it's shaft (the centre shaft). This green gearwheel will only drive the green gearwheel on the outer shaft. The green gearwheel on the outer shaft will only rotate the orange gearwheel on the centre shaft which will also rotate the centre shaft. The orange gearwheel on the centre shaft will drive the orange gearwheel on the outer shaft which will also rotate the outer shaft.
In the above scenario, the longer shaft (the output or drive shaft) can either be placed in the centre or on the edge of the gearbox. If it is placed on the edge, it will rotate slower than if it were placed in the centre (in the above example).
Gearbox Reduction Ratios
The gearbox provides six reduction ratios - 4:1, 16:1, 64:1, 256:1, 1024:1 and 4096:1. This means that the output shaft will turn four times slower than the motor speed with a 4:1 reduction ratio. With a 4096:1 reduction ratio, the output shaft will rotate 4096 times slower than the motor speed.
The assembly is pretty straight forward and is shown nicely in the video. Assembly instructions are also provided on one of the printed pages found in the box.