1-7. LOCATION AND DESCRIPTION OF MAJOR COMPONENTS.
The MLC 70 upgraded bridge folds at the center sections only. The flexible hydraulic lines
between ramp sections and center section have been replaced with hard hydraulic piping.
a. AVLB Hydraulic System. The bridge hydraulic system consists of all the components and
mechanics required to extend and retrieve the bridge (see FIGURE 1-4). The lines, cylinders and
connectors each play a role in the operation of the bridge. The bridge needs 3800 pounds per square
inch (PSI) minimum pressure to operate. The hydraulic pump used to generate the pressure is in the
launcher. It is driven by the engine through a power take-off and a manual clutch. The control valve
bank directs the pressure to the cap or rod end of the actuating cylinder. The fluid is supplied to the
bridge by connecting lines and hydraulic cables. These lines and cables are attached to the lines of the
bridge by quick-disconnect connectors. The bridge disconnects itself when launched which reduces the
exposure of the soldier to enemy fire. The bridge uses FRH type hydraulic fluid. A hydraulic filter is
located in the system to remove any impurities that might pollute the system and cause the hydraulics to
b. AVLB Structural System. The structural system is made up of the sections, braces, supports,
curbing, and connecting hardware (see FIGURE 1-5). The bridge is made of aluminum with steel rivets
and bolts used to secure the components. The scissoring action of the bridge is a result of the extension
or retraction of the scissor cylinder. The piston of the scissor cylinder retracts which, in effect, shortens
the length of the actuating arm and cables. This results in the extension of the bridge. The reverse of
this process allows the bridge to fold under the weight of gravity when it is being held in the upright
position. The forces exerted on the scissoring components of the bridge deteriorate the moving
components. Frequent checks must be made to make sure the bridge is sound. These checks are
addressed in Preventive Maintenance Checks and Services (PMCS) in Chapter 2.
The following features readily identify the (MLC 70) AVLB. Refer to Figure 1-5.
Male and female sections stenciled with 70 enclosed in circle
Two weight limit signs stenciled with 70 are mounted on far and near rear transverse braces
Lower pins, securing ramp to center section, replaced by support beam
also shows the bridge in launched position. Table 1-1 lists the item, quantity, NSN, and item number of
1-6 Change 2