PAGE 24 — HTN 31V
HHN 31V • RIDE-ON POWER TROWEL — OPERATION & PARTS MANUAL — REV. #5 (03/02/07) — PAGE 24
HHN -31V — MAINTENANCE
Blade Pitch Adjustment Procedure
The maintenance adjustment of blade pitch is an adjustment
that is made by a bolt (Figure 19) 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.
There are some things to look for when checking to see if
adjustment is 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? Do the pitch control towers rock back and forth? These
are some of the indications that the blade pitch may need to be
adjusted using the adjustment bolts on the trowel blade finger.
It will be possible to adjust the “high” bolts down to the level of
the one that is not touching, or adjust the “low” bolt up to the level
of the higher ones. If possible, adjust the low bolt up to the level
of the rest of the bolts. This is the fastest way, but may not always
work. Verify that after adjustment, the blades pitch correctly.
Often times, if the blades are incorrectly adjusted, they will not
be able to pitch flat. This occurs when the adjusting bolts have
been raised too high. Conversely, sometimes the adjusting bolts
are too low and the blades cannot be pitched high enough for
finishing operations.
Changing A Blade
Whiteman recommends that all the blades on the entire machine
be changed at the same time. If only one or some of the blades
are changed at one time, the machine will not finish concrete
consistently and the machine may wobble or bounce.
1.
Place the machine on a flat, level surface. Adjust the blade
pitch control to make the blades as flat as possible. Note
the blade orientation on the trowel arm. This is important
for ride-on trowels as the two sets of blades counter-rotate.
Lift the machine up, placing blocks under the main guard
ring to support it.
2.
Remove the bolts and lock washers on the trowel arm, and
then remove the blade.
3.
Scrape all concrete and debris from the trowel arm. This is
important to properly seat the new blade.
4.
Install the new blade, maintaining the proper orientation
for direction of rotation.
5.
Affix the bolts and lock washers.
6.
Repeat steps 2-5 for all remaining blades.
Steering Adjustment
The steering assist adjustment is to be performed only by
qualified service technicians. For HHN steering adjustment
instructions, reference MQ Whiteman service bulletin 200925
Ttt
Clean-Up
Never allow concrete to harden on the power trowel. Immediately
after use wash any concrete off the trowel with water, be careful
not to spray a hot engine or muffler. An old paint brush or broom
may help loosen any concrete that has started to harden.
Figure 19. Blade Pitch Adjustment Bolt
The easiest and most consistent way to make this adjustment is
to use the Trowel Arm Adjustment Fixture (P.N. 9177) . This fixture
will allow consistent adjustment of the trowel arm fingers. It comes
with all the hardware necessary to properly accomplish this
maintenance and instructions on how to properly utilize this tool.
Adjusting the trowel arm fingers without a fixture requires a special
talent.
If a trowel arm adjustment fixture is not available and immediate
adjustment is necessary; we suggest the following procedure. If
you can see or feel which blade is pulling harder, adjust the bolt
that corresponds to that blade.
Another way to determine which blades need adjustment is to
place the machine on a flat surface and pitch the blades as flat
as possible. Now, look at the adjustment bolts. They should all
barely make contact with the lower wear plate on the spider. If
you can see that one of them is not making contact; some
adjustment will be necessary.
