The 1-G LRV trainer was built by GM's Delco Electronics Division in Santa Barbara. Of necessity, it had numerous differences required for operation on Earth. Whereas the LRV was designed to operate on the lunar surface having % the gravity of Earth, the 1-G trainer had to, in effect, be reverse-engineered to withstand six times its originally designed load and stress parameters, and to take into account other factors. The 1-G trainer had no requirement for deployment with folding forward and rear chassis, so the entire chassis was engineered and subsequently built to be fixed and rigid. The aluminum wheel rim was configured to accommodate pneumatic tires. GM engineered heavy duty wire mesh wheels for the 1-G trainer, but these were rarely used. The traction drive for each wheel used 34 VDC motors and a three-stage planetary gearbox instead of harmonic drive; these traction drives were not hermetically sealed. Specific thermal sensors were used on the gearbox to provide overheating indicators on the control panel. Wheel decoupling was simulated on the 1-G trainer to duplicate the LRV-to-crew interface. To properly brake the vehicle, GM designed hydraulically-actuated disc brakes for each wheel which were controlled through the hand controller. Torsion bars were installed only on the lower control arms.
The 1-G trainer employed a continuously-operating steering motor actuated through the hand controller that energized counter-rotating particle clutches. Decoupling of the steering could be simulated, like the wheel decoupling. The hand controller operated in the same manner as the LRV with the same degree of movement for vehicle control regarding vehicle speed, steering and braking. The batteries differed on the 1-G trainer, being rechargeable 34 VDC nickel-cadmium batteries. Both batteries had to be used during operation of the 1-G trainer. Battery temperature was maintained using thermostatically-controlled fans and no thermal blankets were used. The navigation system was identical to the LRV and although calibrated for the wire wheels, the pneumatic tires were nearly identical in diameter so the losses were negligible. Changes to the crew station included the addition of seat cushions and floor panels of flat aluminum plate instead of beaded panels. Thermal control of this trainer was accomplished primarily through convection into the atmosphere, with fan motors used on key components rather than the more sophistical system used on the LRV, as described in Chapter 1. The LRV was designed for an actual gross payload of 436 kg, or 73 kg on the Moon, whereas the 1-G trainer could sustain 362 kg of payload. The 1-G trainer also had its own maintenance schedule and this was outlined in Boeing's Lunar Roving Vehicle Operations Handbook.
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