Relax Mechanism

TM 5-5420-279-23

Fig 1.6 Slide Frame

1-10-21 Relax Mechanism

The relax mechanism forms part of the attachment of the inner slide frame to the vehicle

chassis. It isolates movement of the slide frame during launch beam and bridge construction,

which tend to cant the A-Frame forward or rearward out of vertical. Isolation of the slide frame

movement prevents a rearward pull on the vehicle towards the gap and possible damage to the

crane stabilizer legs. The mechanism is unlocked by manual operation of shoot bolts and allows a

controlled sliding movement of 3 in (80 mm) if the A-Frame tends to cant towards the gap and 1

in (25 mm) if it tends to cant away from the gap, dependent on site and build conditions.

Four hydraulic cylinders are used to re-set the relax mechanism to its neutral position on

completion of bridging operations. The cylinders, acting in pairs (each pair controlling 3 in (80

mm) and 1 in (25 mm) movement), are actuated from the control box on the right side of the

launcher vehicle to the rear of the crane. Movement of the cylinders re-aligns the holes to install

the shoot bolts, locking the relax mechanism back in its neutral setting ready for the next

deployment. Limit switches, operated by the shoot bolts, prevent operation of the launch chest

pack controls until the relax mechanism is unlocked for operation.

1-10-22 Tilt Rollers

The two tilt rollers maintain tension on the carriage slings during bridging operations. They are

operated by hydraulic cylinders fitted to the slide frame and adjust the bridge angle to

compensate for the launch beam angle created by varying bank heights.

1-15