DETAILED DESCRIPTIONS

TM 5-5420-279-23

The A-Frame assembly consists of foldout support legs that allow the vehicle to be leveled

and stabilized for bridge deployment and an upper beam that supports the launch frame. This

upper beam is used in its lower position for launch beam deployment and is raised to provide

clearance for the modular bridge sections during bridge deployment.

The operation of the drive mechanism, winches and hydraulic cylinders is controlled via the

chest pack. The operator of the chest pack controls the whole bridge deployment operation,

which relies on coordinated actions of the 8-man crew in order to achieve minimum deployment

times.

1-10 DETAILED DESCRIPTIONS

1-10-1

Power Take Off (PTO) and Hydraulic Pump

A pump provides the hydraulic power to operate the equipment services. The pump powers

the bridging hydraulic circuits and the crane services from a power take-off on the vehicle

transmission.

The pump is a Standard A11VO75 variable displacement swash plate piston pump driven

via a power take-off (PTO) and drive shaft from the vehicle transmission.

The pump weighs approximately 132 lb. (60 kg) and can produce a flow of 26.4 to 31.68

US gallons (100 to 120 liters) per minute at a pressure of 4423 Psi (30495.51 kPa). It contains

pressure cut-off and load sensing control facilities, which match the flow and pressure outputs of

the pump to the service required. When no services are being selected, the pump reverts to an

idling pressure of 294 Psi (2027.05 kPa) which reduces pump and other hydraulic component

wear and extends their working life.

Cross connection is provided to allow another suitable hydraulic system to be connected to

the DSB Launcher system in the event of a pump failure due to pump or prime mover failure. This

allows the Launcher to complete its mission at a lower speed.

The cross connection system is designed to use the donor vehicle hydraulic system to

drive the DSB without interchanging fluid and the risk of overfilling one or the other reservoirs due

to cylinder motion. It also intensifies the pressure to allow the crane to lift the maximum even if

the donor vehicle does not give sufficient pressure.

It works by having a hydraulic motor driven by the hydraulic system of the donor vehicle

driving a hydraulic pump that works off the DSB hydraulic reservoir.

1-10-2

Crane System

The crane system is used to transfer the launch beam and bridging modules from their

transportation vehicles to the launcher vehicle during bridging operations. The system comprises

an Atlas 390.1 LM Plus crane, a launch beam lifter for the launch beam modules and a two-

position bridge module lifter for use with the bridging modules.