单项选择题
Wristpin bearings are difficult to lubricate because of their oscillating motion and（）
A.their free-floating design
B.their relatively small size
C.the reciprocating motion of the piston
D.their position in the lubrication system
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相关考题
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Internal combustion engine crankcase vent outlets must be equipped with （）
A.hinged rain guards
B.corrosion resistant flame screens
C.dipsticks for measuring oil levels
D.crankcase ventilation fans -
单项选择题
The interior of some diesel engine saltwater heat exchangers are protected from corrosion by the use of（）
A.aluminum plates
B.lead cathodes
C.copper baffle plates
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单项选择题
Proper lubrication of the main bearing is more easily obtained in a single acting four-stroke/cycle diesel engine than in a single acting two-stroke/cycle diesel engine because （）
A.bearing pressure in a four-stroke\cycle acting single diesel engine is continually reversed
B.bearing pressure in a two-stroke\cycle single acting diesel engine is continually reversed
C.the maximum bearing pressure is higher in a single acting two-stroke/cycle diesel engine
D.two-stoke/cycle diesel engines require more complicated lubrication piping
