FIRST Global Building Guide Created by REV Robotics 2019, Licensed Under CC BY-SA
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3.12.1
Chain Tension
In order for sprockets to work effectively, it is important that the center-to-center distance is correctly adjusted. The
sprocket and chain in Figure 54 may work under very light load, but they will certainly not work and will skip under any
significant loading. The sprockets in this example are too close together so chain is loose enough that it can skip on the
sprocket teeth. The sprockets in Figure 55 are correctly spaced which will provide smooth, reliable operation.
Figure 54: Incorrectly Spaced Sprockets (Chain too Loose)
Figure 55: Correctly Spaced Sprockets (Chain Correctly Tensioned)
To correctly space REV Robotics sprockets, use the following procedure:
1.
Securely fix the axle of either the input or output sprocket. In the case of a gear train with multiple idlers or a
compound reduction, consider which axle makes the most sense to fix such as the very first input gear or the very
last gear.
2.
Starting with the fixed axle, then identify all the driving and driven sprockets for any sprockets on that axle. One by
one loosen these axles, slide them until the chain is tensioned and then retighten the axle mounts.
3.
Continue the procedure from Step 2 for each fixed axle until all the chains are tight and all the axles have been
retightened.
3.12.2
Anatomy of Chain
Roller chain is used to connect two sprockets together and transfer torque. Roller chain is made up of a series of inner
and outer links connected together to form a flexible strand (Figure 56).
Figure 56: Basic Chain Nomenclature
Outside Links
consist of two outside plates which are connected by two
pins
that are pressed into each plate. The
pins
in the outside link go through the inside of the hollow
bushings
when the inner and outer links are assembled.
The
pins
can freely spin on the inside of the
bushings
.
Inside Link
consist of two inside plates that are connected by two hollow
bushings
which are pressed into each
plate. The teeth of the sprocket contact the surface of the
bushings
when the chain is wrapped around a sprocket.
