Fifth Wheels Holland Fifth Wheels General Information shoulder and neck of the kingpin, positioning sliding yokes between the lock halves and tapered rib mem- bers of the fifth wheel understructure. The kingpin can be released only by manually operating the kingpin lock control handle. The adjustment nut will compensate for wear on the lock or kingpin. Holland fifth wheels ( Fig. 11.1 ) are bracket-mounted to the tractor frame in a position that best distributes the trailer load over the tractor axles. The Holland Lockguard ( Fig. 11.3 ) is a device that pre- vents a false lockup, and is used with Type "B" kingpin lock mechanisms.
The Lockguard is a spring-tensioned, smooth-surfaced tongue that the kingpin passes over and depresses when entering the lock mechanism. The Lockguard will prevent the locks from engaging before the kingpin fully enters the locks. If the kingpin enters the fifth wheel incorrectly and does not depress the tongue, the locks are unable to close. 1 2 The Type "A" kingpin lock mechanism ( Fig. 11.4 ) uti- lizes a single hinged lock and cam arm. The final for- ward motion of the kingpin into the open lock forces the hinged lock to pivot on a pin and close around the king- pin. The lock is held in place by a spring loaded plunger.
The kingpin can be released only by manually operating the release handle. The adjustment nut will compensate for wear on the lock or kingpin. 10/31/94 f310266a 1. Kingpin Lock Release Handle 2. Kingpin Lock Mechanism Fig. 11.1, Holland Fifth Wheel Fifth Wheel Locking Operation The Type "B" kingpin lock mechanism ( Fig. 11.2 ) uti- lizes two spring-loaded lock halves. The final forward motion of the kingpin into the open lock halves forces the locks to close in a 360 degree grip around the Locking the Fifth Wheel Mechanism 1. Chock the front and rear of the trailer tires to pre- vent the trailer from moving. 11.1