Gradall G-550C Operation And Maintenance Manual page 26

G-660C & G-880C GRADALL (Crawler)
The tracks should be kept tight enough so that there is
only a limited amount of sag between the drive
sprocket and the top center roller. Using a straight
edge, measure the sag. It should be maintained to no
more than 1.187" or 30 mm. If adjustment is required,
add grease to the tensioning cylinder until the sag is
reduced
TRACKS TOO TIGHT
If a track is adjusted too tight, a great amount of friction
will exist between the pins and bushings when the
track links hinge as they travel around the sprocket
and idler. This friction causes accelerated wear to the
pins, bushings, links, sprocket and idler. Friction in a
tight track also robs the machine of much horsepower.
Severely tight track adjustment can cause the track to
run extremely hot and "draw-back" the hardness of
pins and bushings. In some extreme instances the pins
and bushings may become so hot that they fuse
together.
Also, an extremely tight track adjustment can cause
severe damage to the final drive hubs, bearings and
gears.
Strange but true, the mechanical law of undercarriage
wear rules that whether the track goes forward or
backward, internal pin and bushing wear always
occurs on only one side. (Compare your track chain to
a common log chain. The wear is always the same
regardless of which end is pulled).
TRACK TIGHTNESS
TRACKS TOO LOOSE
On the other hand, if the track adjustment is too loose,
service life is similarly reduced. Loose track fails to
stay aligned properly and tends to come off when the
machine is turned, causing wear to the idler center
flanges, roller flanges and the sides of the sprocket
teeth. A loose track tension adjustment also permits
the sprocket to jump teeth easily, especially in reverse,
causing unnecessary wear to sprocket teeth and track
bushings.
CHAIN WEAR
Each link of the chain is made up with the pin on one
end and the bushing on the other. They are joined
together and wear occurs as they move to a changed
angle as they make contact or lose contact with the
drive sprocket.
26
OPERATION & MAINTENANCE