![](https://lstatic.shangxueba.com/jiandati/pc/images/pc_jdt_tittleico.png)
The sealing function of the piston ring is brought about by the gas pressure above and beh
A.upwards / inwards
B.upwards / outwards
C.downwards / inwards
D.downwards / outwards
![](https://lstatic.shangxueba.com/jiandati/pc/images/jdt_panel_vip.png)
A.upwards / inwards
B.upwards / outwards
C.downwards / inwards
D.downwards / outwards
The main advantage of improved Simplex tailshaft seal are____.
A.the good sealing performance and the simple structure
B.the good sealing performance and the short life expectancy
C.the good sealing performance but the short life expectancy
D.the good sealing performance and the lower cost
A、metric thread, trapezoidal thread, sealing pipe thread
B、trapezoidal thread, sealing pipe thread,metric thread
C、trapezoidal thread, ,metric thread,sealing pipe thread
D、metric thread, trapezodial thread, sealing pipe thread
Mr. Luzaich\\\'s attitude to the automatic sealing is ______.
A.opposition
B.suspicion
C.approval
D.indifference
A.digging up
B.sealing off
C.repairing
D.building
Sealing in pump shaft is achieved by means of the _____.
A.gasket
B.packing
C.washer
D.spring
A.Canada had no sealing rights off Alaska.
B.The Canadians could hunt the seals.
C.The United States could claim the seals.
D.The United States could not hunt the seals.
The lowest ring of a piston is _____.
A.a coil spring
B.a sealing ring
C.an oil distributor ring
D.main seal ring
Shaft sealing in a centrifugal pump can be effected by _____.
A.the mechanical seal
B.packed stuffing boxes
C.either A or B
D.neither A nor B
Sealing in pump shaft is achieved by means of the ().
A.gasket
B.packing
C.o-ring
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