b. Maintenance.
(1) Sight level gage (fig. 3-15). Check the hydraulic oil level before and after operation. If the oil level disappears from the
sight gage, report to organizational maintenance.
(2) Ramp descent control. The LARC is equipped with two fluid flow restrictors (fig. 3-16). The restrictors control the rate of
ramp descent by restricting the hydraulic fluid flow back from the ramp cylinders to the hydraulic oil supply tank. These restrictors
are located between frames 7 and 8, one port and one starboard, just forward of the multiple unit valves. The fluid flow back from
each ramp cylinder is individually controlled by its corresponding fluid flow restrictor. The ramp should require 10 to 15 seconds to
descent from full closed to full open position. If ramp descent time exceeds the specified limits, report to organizational maintenance.
Figure 3-16. Port ramp descent control.
(3) Operator- personnel are not authorized to perform maintenance on hydraulic components.
Report all defects to
organizational maintenance.
3-10. Land Drive System
a. Description. The LARC is equipped with a four-wheel drive system. Each wheel is independently driven by a diesel engine. The
four diesel engines transmit power from their flywheel ends through the respective torque converters, flexible couplings,
transmissions, miter boxes, column and wheel drives, and wheels. Airbrakes for the LARC are located on the forward and aft sides of
each miter box.
(1) Torque converter. The torque converter is connected directly to the engine. The converter protects the engine from
damaging shock loads and harmful engine lugging or stalling. It employs the rotating housing principle. The converter elements are
enclosed in a housing consisting of converter flywheel and converter pump. The converter flywheel is driven by the engine crankshaft
through a flexible flywheel disc assembly. Two stators, which are designed so they can freewheel or automatically lockup, provide
the necessary reaction for torque multiplication by the converter. A turbine element is connected to the output shaft and delivers
the output power of the converter. Operation of the converter is as follows:
(a) Engine rotation causes the converter pump element to rotate, forcing the oil in the converter to rotate also.
(b) The motion of the oil is such that it strikes the turbine element causing the turbine to move.
(c) At low speed or during starting, the oil motion attempts to force the two stators to run backwards, but roller cams in
the stators prevent backward rotation. The result is a multiplication of the engine torque and a reduction in the output speed.
(d) At higher speeds, the direction of the oil motion changes so that the first stator begins to rotate in the same direction
as the pump and turbine. The torque multiplication effect decreases and the converter output speed increases.
(e) As the output speed increases further, the second stator starts to rotate. At this point, both the pump and the turbine
are running at approximately the same speed and the converter is functioning essentially as a fluid coupling.
(f) An increase in load causes first one stator and then the other to stop rotating, resulting in increased torque at lower
output speed. The action is automatic and functions continuously and smoothly, thereby greatly reducing transmission of shock
loads to the engine.
(2)
Flexible couplings. Flexible couplings are used between the torque converter and the
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