Checking Shaft Bearings For Looseness Figure 10
CHECKING & ADJUSTING TRACK DRIVE TRANSFER CASES
The two transfer cases for the track drive system can best be protected against shock loading and
subsequent bearing wear by keeping the tracks and the drive chains properly tightened and well lubricated.
When a paver is operated with loose tracks and drive chains, shock loading occurs each time the travel
clutches and brakes are engaged. The tapered roller bearings and gears on the output shaft, and the ball
bearings and pinion on the stub shaft, are subjected to extreme stress each time the paver starts and stops.
Extreme drive loading also occurs when tracks and drive chains are allowed to accumulate a coating of
hardened asphalt. It is important that they be spray cleaned and lubricated thoroughly with fuel oil after each
days operation so that the asphalt remains soft and drops off during subsequent operation. When
excessive loading is allowed to occur due to inadequate spray cleaning, the drive chains are stretched and
develop the looseness that increases shock loading.
It is recommended that the tension of the drive chains be checked after each week of operation. When
correctly tightened a drive chain can just barely be deflected by hand. It should not be drawn up "drum tight".
It is also recommended that anytime a loose chain is to be tightened, the output shaft of that transfer case
be carefully checked for looseness.
This can be done as follows:
(1) With paver engine stopped and track brakes Off, turn the clutch rotor on the transfer case so that
there is an equal amount of slack in the drive chain on both sides of the sprocket.
(2) Using a pry bar and some blocking as shown in Figure 10, put some upward pressure on the output
shaft and see if any vertical movement of the shaft is noticeable. Exert some end wise pressure on the shaft in
both directions and see if any horizontal movement of the shaft is noticeable. The output shaft bearings are
pre-loaded at assembly and there should be no movement possible in any direction. If there is noticeable
movement it is strongly recommended that the transfer case be repaired or adjusted so that a part failure does
not occur during operation. The cost of inspection, adjustment, replacement, or field repair during an out-of-
service maintenance period is far less than the cost of a break-down during paving.
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