单项选择题
A.flat surface B.mirror finish C.sloping surface D.inclined surface
The load on the crosshead pin is always （）, so it is th...
单项选择题The load on the crosshead pin is always （）, so it is the （）half of the bearing which is subject to wear.
A.upwards；top B.upwards；bottom C.downwards；top D.downwards；bottom
Because the top of the connecting rod swings about the ...
单项选择题Because the top of the connecting rod swings about the pin and changes direction each time the piston reaches mid-stroke, the relative speed between bearing and pin at mid-stroke is zero, （）to a maximum as the piston approaches top or bottom dead center and then （） back to zero again as the piston approaches mid-stroke and the connecting rod changes direction.
A.accelerates；decelerates B.accelerates；accelerates C.decelerates；decelerates D.decelerates；accelerates
The slippers run （） in the crosshead guides as the pist...
单项选择题The slippers run （） in the crosshead guides as the piston and rod are （）and prevent the top of the connecting rod from moving sideways.
A.up and down；reciprocating B.up and down；rotating C.back and forth；reciprocating D.back and forth；rotating
