ARMY TM 5-5420-212-23
MARINE CORPS TM 08676A-23/2
Roller Beam (RB)
The roller beam allows the bridge to be boomed (moved) when needed during construction, and is required for
the building of any MGB, regardless of length.
Roller beam is placed on fixed supports for single story, or in adjustable supports for double story and linked
reinforced bridges. Ideal conditions (perfectly level ground) will permit placement of the roller beam on the ground or
Roller catches MUST NOT be engaged when the bridge is moving over the roller beam, otherwise
damage to the bridge and roller beams will occur and the roller beam could tip over.
(1) CENTER ROLLERS. Permits light launching nose and bankseat beam to ride over roller beam during single story
(2) OUTER ROLLERS. During MGB construction bridge girders roll over two pairs of outer rollers. The outer roller of
each pair is flanged and slotted so that the roller can engage with the roller catch and be locked.
(3) ROLLER CATCH. Used to lock outer flanged rollers.
(4) JACK HOOD. Used in double story construction for placement of hydraulic jack head.
(5) PINS, FIXED AND RETRACTABLE. Used to hold roller beam in adjustable support.
(6) IDENTIFICATION PLATE. The component serial number is marked on this plate.