This rod is basically a turnbuckle (Figure 22). Rotating it in one direction increases the length and corresponding trowel speed. Rotating it the opposite direction decreases the length and trowel speed.The right side trowel speed should be within 3 rpm of the left.
Figure 22. Turnbuckle & Adjustment Nuts
A good starting point in the adjustment process is to adjust the rod such that both trowels begin to rotate at the same time when the foot pedal is slowly depressed. This will, generally, get the speeds fairly close; close enough for use if instrumentation is unavailable (i.e.on the job site). From this point on, some form of instrumentation is required to verify that the trowel speeds are within tolerance. A strobe or magnetic pickup type speed indicator is recommended to verify the speeds.
The trowel speeds should be adjusted on a dry concrete floor with the blades pitched flat. Units with the John Deere turbocharged engine should be set at
STX-SERIES — MAINTENANCE
Matching Blade Pitch for Both Sets of Blades
Sometimes it may be necessary to match blade pitch between the left and right sets of blades. There are some signs that this may be necessary. For example, the differences in pitch can cause a noticeable difference in finish quality between the left and right sets of blades. The difference in blade pitch can also make the machine difficult to control. This is due to the surface area in contact with the concrete (the blade set with the greater contact area tends to stick to the concrete more).
To synchronize pitch on both sides, the left blade assembly can be pitched by itself. By using the electric blade pitch rocker switches, (Figure 23) the pitch can be syncronized on the left and the right sides.
LEFT | TWIN |
PITCH MORE PITCH | PITCH |
ONLY LESS PITCH |
|
BLADES TO BE FLAT
WITH FLOAT PANS
Figure 23. Blade Pitch Rocker Switches
Blade Pitch Adjustment Procedure
The maintenance adjustment of blade pitch is an adjustment that is made by a bolt (Figure 24) on the arm of the trowel blade finger.This bolt is the contact point of the trowel arm to the lower wear plate on the thrust collar.The goal of adjustment is to promote consistent blade pitch and finishing quality.
Watch for the following indications when determining if blade pitch adjustments are necessary:
■Is the machine wearing out blades unevenly (i.e. one blade is completely worn out while the others look new)?
■Does the machine have a perceptible rolling or bouncing motion when in use?
■Look at the machine while it is running, do the guard rings “rock up and down” relative to the ground?
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