Reasons for Flex Coupler Failure
When Flex Couplings are returned on a warranty claim, the coupling is
examined for signs of manufacturing defect and abuse. More times than
not they show indications of abuse. There are five major causes for
premature Flex Coupling failure:
1. Improper maintenance or adjustment: Due to bearing adjustment, stop
adjustment, or worn shocks or air cylinders, the Wrap arms are restricted
or inhibited in their movement. The Wrap coupling then has to make the
adjustment and the coupling is repeatedly flexed too far, causing it to
eventually fail. See the Wrap install guide for Wrap setup guidance, and
call with additional questions.
2. Wrap gets caught: Wraps can get caught on protrusions extending from
the vehicle. Trailer hitches are notorious, but rear windshield wipers, spare
tires brackets, bent bumpers, loose trim, body damage, roof racks, even
spoilers can catch Wraps, particularly if they are not adjusted properly (see
item 1). Some of these dangers cannot be totally avoided, especially in
unattended express tunnels, but they can be minimized. When a Wrap
gets caught, the conveyor and the Wrap equipment get into a tug of war
for the vehicle. The Wrap Coupling is bent sharply and damaged while
being turned by the hydraulic motor.
3. Wrap height: This is rare, but it happens. Make sure that the Wrap frame
is set high enough that the driver side Wrap core clears the higher
conveyor rails by at least 2”. If the Wrap is too low, it will constantly swing
back and forth in a semi-circular pattern as it grabs the rails. The Flex
coupling eventually wears out from the constant bending.
4. Wrap torque: This is the most overlooked aspect affecting Flex
Couplings and most common issue. At installation, the torque relief
(hydraulic pressure relief) on ALL the hydraulic flow control valves on each
circuit should be adjusted. If the torque is high, every time the brush turns\
on it will slam hard on the flex joint and fatigue the flex material. This
pressure should be set just high enough so that the brushes never slow
down at any point in their normal cycle on any vehicle, BUT no higher. This
allows a Wrap or any other brush to stall when it is caught by something,
greatly reducing the chance of damage to the vehicle or equipment. This
parameter is very frequently not set properly at installation. Tommy Car
Wash Systems offers a free operator training course to assist you with
understanding the operation of the hydraulic system.