THEORY OF OPERATION AND EQUIPMENT DATA (Contd)
FUNCTION OF THE LAUNCHER MECHANISM (Contd)
The lower support boom functions to lift the launch boom under the weight of the bridge as the
bridge is coupled, extended, and emplaced. Two large hydraulic cylinders connected to the lower
support boom provide the necessary force.
The pin wheel drive units function to drive and retain the bridge, by means of the bridge launch
beam, during launch and retrieval. The gear on each pin wheel drive unit is designed to engage with
pins on the bridge launch beam to move the bridge. A hydraulic brake on the rear pin wheel drive
unit holds the bridge by means of locking the pin wheel drive gear.
The secondary boom functions to lower the upper bridge half during coupling and lifts the upper
bridge half during uncoupling. Two rollers on the secondary boom keep the upper bridge half
centered with the lower bridge half for alignment during coupling.
The winch functions to lower the ramp end of the upper bridge half by its launch beam prior to
coupling, and takes control of the bridge after coupling by lowering the bridge to the ground.
HOW THE BRIDGE IS EMPLACED
In order to launch the bridge, the CBT is positioned on the shore, supporting cylinders are lowered, and
the LPU is started. A hand held remote control unit (RCU) is used to operate the pallet launcher
mechanism. Within the RCU is an electronic Stored Program System (SPS) containing 22 functional steps
required to expand, couple, extend, and emplace the bridge. Each functional step is initiated by the operator
and is carried out either automatically by the SPS or manually by the operator. Essentially, the two bridge
halves are first expanded to roadway width. Then the lower bridge is driven out to the rear by the pallet's
pin wheel drive units. The upper bridge half is lowered and positioned so that the lower couplings of both
bridge halves are engaged. Then the lower bridge half is tilted toward the upper bridge half until the upper
couplings on both bridge halves lock. The coupled bridge is then driven to the rear until the entire length of
the bridge is extended over gap (river, gully, or ditch) to be crossed. The pallet launch boom and lower
support loom lower far shore end of bridge to ground, and the pallet winch lowers near shore end to ground.
Bridge retrieval is performed basically in reverse order.
END OF WORK PACKAGE