Glossary “rolling radius” Definition:
The distance between the center of the wheel and the contact points of the tire on the ground under the weight of a vehicle.
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rolling resistance
Glossary “rolling resistance” Definition:
Pounds of force required to overcome the resistance of a tire to rotate.
rolling element bearing
Glossary “rolling element bearing” Definition:
A bearing that rolls on the part that it supports.
rollers
Glossary “rollers” Definition:
Round steel bearing that can be used as the locking element in an overrunning clutch or as the roller element in an antifriction bearing.
rolling
Glossary “rolling” Definition:
A result of overloading and sliding, which leaves a burr on the tooth edge. Insufficient bearing support results in rolling of the metal due to the sliding pressure.
rolling diameter
Glossary “rolling diameter” Definition:
Term used for tire rolling diameter.
roller clutch
Glossary “roller clutch” Definition:
A one-way clutch containing a number of rollers that operate by wedging on a ramp between an inner and outer race to lock up (drive) when the outer race is turned in one direction, and to slip (overrun) when it is turned in the opposite direction.
roller hydraulic lifter
Glossary “roller hydraulic lifter” Definition:
Lifters with rollers placed at the base to limit lifter/cam friction.
roller lifter
Glossary “roller lifter” Definition:
A valve lifter, featuring a roller which contacts the camshaft to reduce friction.
roller tappet
Glossary “roller tappet” Definition:
Valve lifter or tappet with a roller that rides on the camshaft lobe. Either solid or hydraulic lifters can be roller tappets.
roller bearing
Glossary “roller bearing” Definition:
Bearing using rollers within an outer race or ring.
roller cam
Glossary “roller cam” Definition:
Camshaft having a small roller at the base of each lifter.
roller chain
Glossary “roller chain” Definition:
A timing chain having rollers that engage the gear sprockets.
roll stiffness
Glossary “roll stiffness” Definition:
The resistance, measured in pounds per inch of spring travel, of a suspension system to the rolling of the vehicle’s mass.
rolled edge clamps
Glossary “rolled edge clamps” Definition:
Hose clamps used for fuel injection and other high pressure uses. They are designed so that they will not cut into the hose.
roller
Glossary “roller” Definition:
Cylindrical locking element of a one-way roller clutch, or the rotating part of a roller bearing.
roll centers
Glossary “roll centers” Definition:
The points at the front and rear about which the vehicle’s spring mass will roll.
roll out
Glossary “roll out” Definition:
The distance a race car travels in a drag-racing event at the beginning of a run before the front tires clear the stage beam and start the clock.
roll over valve
Glossary “roll over valve” Definition:
Valve in the vent line from the fuel tank that blocks the line if the vehicle is in an accident and rolls over, preventing liquid fuel from being able to leak out.
roll steer
Glossary “roll steer” Definition:
The direction and amount that the rear axle may cause the vehicle to steer as it moves through its travel when the body rolls during cornering requiring the driver to oversteer or understeer to compensate for the problem.