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Wheels and power[edit]

Close-up of wheel showing chevron treads

The wheels were designed by General Motors Defense Research Laboratories. The manufacturing was subcontracted out to Goodyear who then sub contracted Rex-Nord to make the wheel halves. Many past and present employees at Rex-Nord signed the halves before they were riveted together. Ferenc Pavlics was given special recognition by NASA for developing the "resilient wheel".[21] They consisted of a spun aluminum hub and a 32 inches (81 cm) diameter, 9 inches (23 cm) wide tire made of zinc-coated woven 0.033 inches (0.84 mm) diameter steel strands attached to the rim and discs of formed aluminum. Titanium chevrons covered 50 percent of the contact area to provide traction. Inside the tire was a 25.5 inches (65 cm) diameter bump stop frame to protect the hub. Dust guards were mounted above the wheels. Each wheel had its own electric drive made by Delco, a direct current (DC) series-wound motor capable of 0.25 horsepower (190 W) at 10,000 rpm, attached to the wheel via an 80:1 harmonic drive, and a mechanical brake unit.

Maneuvering capability was provided through the use of front and rear steering motors. Each series-wound DC steering motor was capable of 0.1 horsepower (75 W). The front and rear wheels would turn in opposite directions to achieve a tight turning radius of 10 feet (3 m), or could be decoupled so only front or rear would be used for steering. They could free-wheel in case of drive failure.

Power was provided by two 36-volt silver-zinc potassium hydroxide non-rechargeable batteries with a capacity of 121 A·h each (a total of 242 A·h), translating into a range of 57 miles (92 km).[15] These were used to power the drive and steering motors and also a 36-volt utility outlet mounted on the front of the LRV to power the communications relay unit or the TV camera. LRV batteries and electronics were passively cooled, using change-of-phase wax thermal capacitor packages and reflective, upward-facing radiating surfaces. While driving, radiators were covered with mylar blankets to minimize dust accumulation. When stopped, the astronauts would open the blankets, and manually remove excess dust from the cooling surfaces with hand brushes.

Edited by Jon Haigwood
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