單項選擇題Many diesel engine exhaust valves are being constructed with hollow stems filled with sodium in order to （）

A.provide added wear protection against today’s corrosive quality of fuel
B.increase overall valve strength due to the high gas pressures
C.assist in dissipating heat due to the extreme operating temperatures
D.reduce the overall weight of the valve thus helping eliminate valve spring surge and hammering


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1.單項選擇題Cracking of a diesel piston crown can result from（）

A.Excessive piston to liner clearance
B.The underside of the piston crown being excessively dirty lowering the rate of heat transfer
C.Faulty nozzle spray
D.All of the above

2.單項選擇題In an auxiliary diesel engine, the reason for knurling the piston skirt is to（）

A.improve skirt lubrication
B.allow for expansion
C.transmit forces evenly
D.improve the piston seal

3.單項選擇題Which of the listed design features is found in an exhaust valve and NOT in an intake valve?（）

A.Hard alloy steel construction
B.Beveled edges on the valve head
C.Low alloy steel construction
D.Poppet type design

4.單項選擇題A diesel engine cylinder head can crack as a result of （）

A.a leaking seal ring
B.heat transfer from exhaust valves
C.restricted cooling passages
D.overheated intake valves

5.單項選擇題In large, low-speed, main propulsion diesel engine, position ring groove wear usually occurs at the（）

A.top of the ring groove
B.back of the ring groove
C.bottom of the ring groove
D.piston ring end clearance