1-18. M1084/M1086 MATERIAL HANDLING CRANE (MHC)
Figure 1-27. M1084/M1086 Material Handling Crane (MHC)
Vehicle models M1084 and M1086 are equipped with a Material Handling Crane (MHC) (1, Figure 1-27) mounted on
the frame at the rear of the vehicle. The M1084/M1086 MHC has a lifting capacity of 5,000 lbs (2,270 kgs). The MHC
contains an overload shutdown system which monitors boom angle, boom extension, and load weight. If the overload
shutdown system senses an overload condition, certain crane functions become locked out. The vehicle is stabilized
during crane operation by jack cylinders (2). Proximity sensors are attached to the jack cylinders to prevent operation
of the crane unless the jack cylinders are extended to the ground. Outrigger pads (3) are provided and are attached
to the bottom of the jack cylinders by quick release pins. All crane functions are hydraulically controlled by levers at
the control station (4). All exposed hydraulic cylinder rods are hard chrome plated to resist corrosion and wear.
a. MHC Hydraulic System. The hydraulic reservoir (5) provides for 21 gal (79 L) of fluid. A fluid filter (6) is mounted
on the hydraulic reservoir. The filter removes contaminants from the oil and is easily replaced. Hydraulic pressure for
the MHC is supplied by a hydraulic pump (7) attched to the rear of the Power Take-Off (PTO) (8). The hydraulic
cylinders contain cartridge-type holding valves which lock the cylinder in case of sudden hydraulic pressure loss. A hand
operated back-up hydraulic pump (9) allows the operator to lower any load to the ground and stow the crane if the
hydraulic pump fails.