27
Service Bay
to work as part of a timing movement
during locking and unlocking.
A fi fth wheel's locking mechanism
should be visibly checked as well.
"Drivers are known to miss things and
make mistakes," Puckett says. "We advise
technicians check the locking mecha-
nism and the pull handle, make sure the
springs are working, activate the [spring]
cylinders [during a PM]. You want to
make sure nothing has been damaged."
Marsh says JOST offers a lock tester
to use during these inspections. The
tester simulates a fi fth wheel locking into
a kingpin and allows the technician to
ensure the connection is secure.
Marsh says a lock tester should be
snug within a fi fth wheel connection but
not immovable.
"You shouldn't have any play and it
shouldn't move [vertically or horizontal-
ly]," he says, "but you want to be able to
rotate the lock tester pin within the lock.
"If you rotate it and you have some
resistance then [the fi fth wheel] is too
tight."
A fi fth wheel that is correctly con-
nected and locked will not come loose,
Puckett says, but that doesn't mean the
lock is immune to wear. Today's kingpins
are extremely robust, and can slowly
weaken the interior of a fi fth wheel lock
over time.
And Marsh advises not to forget the
kingpin when checking a fi fth wheel lock.
A bent or worn kingpin will reduce the
quality of a connection.
Usage also can impact the rate at
which a fi fth wheel wears down. Service
providers should ask their customers
about their duty cycle when cleaning and
maintaining a fi fth wheel.
A fi fth wheel that is pushed to the
brink in severe-duty applications might
require additional maintenance inspec-
tions, the OEMs note.
"Application is critical to the longevity
of the fi fth wheel," says Nissen, adding
that it's a good idea to notify a customer
if they might benefi t from spec'ing a dif-
ferent fi fth wheel option.
"We outline use in our literature:
standard duty, moderate duty and severe
duty," he says. "These classifi cations out-
line what the vehicle is going to see, as to
how much on road versus off road, and
the type of loads as to weight that the
fi fth wheel will be exposed to."
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or call 1.800.876.3929
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