SkyTracker STX-1-2000, Instruction Manual

Page: 17 / 52

5.3 TIMING BELT IDLERS
The timing belt idlers serve to center the timing belt onto the spindle drive pulleys. The tim-
ing belt should not ride on the sides of the drive pulleys, as this condition will cause extraor-
dinary wear to the timing belt. The idlers have been adjusted at the factory and usually do
not need re-adjustment.
5.4 TIMING BELT TENSIONING ADJUSTMENTS
Timing belt tensioning is accomplished by two turnbuckles mounted on motion assemblies
#1 and #3 which are located to the left and the right of the control panel. To tighten the tim-
ing belt, loosen the outermost turnbuckle hexnut and its adjacent locknut. Then loosen (but
do not remove) the four mounting bolts that hold the lower bearing mount to the base and
gradually tighten the two turnbuckles equally. The
slotted holes in the housing permit this
adjustment. The belt tension should be such that its deflection from a straight line (between
points of contact with the drive/timing pulley and idler) is between 1/8" and 1/4" (3-7 mm)
when a force of 50 lb. (22.6 kg) is applied midway between the drive pulley and idler.
After achieving proper belt tension, securely tighten first the turnbuckle locknuts, and then
the four bearing housing mounting bolts on each side.
CAUTION
Tightening the timing belt from one side only may alter the synchronization of
the four lamphouses, causing them to collide in the “up” position.
Proper timing belt tensioning is important. A loose belt may cause the heads
to slip out of synchronization, causing them to hit each other. An overly tight
belt can cause tearing of the reinforcing cords within the belt, leading to pre-
mature belt failure.
5.5 SPRING ASSEMBLIES
Each spring assembly consists of pairs of springs that counterbalance the lamphouses.
The SkyTracker should not be operated with a broken spring for prolonged periods of time,
as this will cause extraordinary wear on the drive system that may result in failure.
A broken spring may be replaced by removing the eyebolt and related spacers on the end
of the spring mounting shaft. See the “Detail” drawing on Page 41.
CAUTION
Springs should be replaced with lamphouses in an upright position, reducing
the tension on the springs.
NOTE: The springs have special screw-on ends with ball joint connectors.
When replacing a spring, the rod end and cap must be removed from the
broken spring and re-installed on the new spring (includes retaining plugs).
After re-assembly and alignment, the steel lock nuts must be tightened to
prevent accidental disassembly. See the “Detail” drawing on Page 41.
13