-
If the compensating needle valve of a hydraulic governor is opened more than necessary the governor will （）
A . have a larger than normal dead band
B . produce excessive speed response to a load change
C . respond slowly to any change in engine load
D . stabilize engine speed at the new governor setting
-
A common trouble with the fuel pump plungers or fuel valve spindle is （）.
A . broken down
B . stuck
C . oil leakage
D . carbonized
-
The purpose of the purge valve at the top of the condenser in a refrigerating system is to（）
A . remove any air that may accumulate in the system
B . take out unpleasant fumes from the refrigerant
C . vent off excess refrigerant in an emergency
D . permit opening the refrigerating system for cleaning and inspecting
-
In its simplest form the pressure reducing valve is opened or closed by （） which is balanced by the downstream pressure acting on a diaphragm.
A . adjusting a nut
B . a pre-tensioned spring
C . any spring
D . upstream pressure
-
The globe valve has a bulbous body, housing a valve seat and screw down plug or disc arranged at right angles to the axis of the pipeAccording to the above sentence, which of the following statements is not true?（）
A . The profile of the valve is like a globe
B . The valve seat is set into the bulbous body
C . The plug or disc of the valve is made vertical to the axis of the pipe
D . The valve seat is located at right side of the plug or disc
-
A(n) （） is a special type of valve which prevents the passage of steam but allows condensate to pass.
A . check valve
B . non-return valve
C . steam trap
D . quick closing tra
-
A large valve，usually installed above the ram preventers，that forms a seal in the annular space between the pipe and wellbore or，if no pipe is present，on the wellbore itself is called the（）.
A . annular blowout preventer
B . annulus
C . accumulator
D . automatic choke
-
A feeler or thermal bulb is used for the expansion valve to （）.
A . detect the temperature
B . detect the pressure
C . heat the refrigerant
D . accelerate the refrigerant
-
If a single cylinder relief valve on a diesel engine lists frequently while the engine is running, the cause may be an （）
A . excessively late injection timing for each cylinder
B . incorrectly adjusted intake valve timing
C . incorrectly adjusted fuel injector
D . incorrectly adjusted intake valve clearance
-
In order to maintain a constant outlet water temperature of 80-85℃ from the engine, a three-way valve is installed（）
A . at the jacket cooler outlet to control the flux through the engine
B . at the jacket cooler outlet to control the flux through the cooler
C . at the engine outlet to control the flux through the engine
D . at the engine inlet to control the flux through the engine
-
A thermostatic expansion valve is properly controlling evaporator superheatAdjusting this valve to lower the superheat will result in a/an （）.
A . evaporator pressure decrease
B . evaporator coil over-feed
C . evaporator capacity increase
D . expansion valve diaphragm rupture
-
If the engine is naturally aspirated, or is a small high-speed type with a centrifugal turbocharger, the period of valve overlap（）,ie when both valves are（）, will be and the exhaust valve will close some 10°top dead canter（）.
A . open；short；after
B . closed；short；after
C . open；long；before
D . closed；long；before
-
A device fitted over the discharge opening on a relief valve consisting of one or two woven wire fabrics is called a（）.
A . flame stopper
B . flame screen
C . flame filter
D . flame restrictor
-
A common trouble with the fuel pump plunger or fuel valve spindle is （）.
A . water leakage
B . steam leakage
C . oil leakage
D . air leakage
-
The purpose of the delivery check valve used in a diesel fuel injection jerk pump is to （）.
A . assist in a quick cutoff of fuel injection
B . allow oil backflow from the injector to the helix
C . reduce fuel oil pressure between injection strokes
D . meter the quantity of fuel delivered
-
Which of the listed statements is a characteristic of the liquid charged power element used with thermostatic expansion valves?（）
A . At the designed operating temperature, the liquid refrigerant charge has changed to a vapor
B . The liquid refrigerant tends to collect at the bellows or diaphragm and reduces the valve sensitivity
C . The sensing bulb is empty of liquid refrigerant charge at the designed operating temperature
D . The sensing bulb is never emptied of liquid refrigerant under normal operating conditio
-
When a refrigeration compressor is in the ‘off’ cycle, the thermal expansion valve will（）.
A . always be wide open when the compressor restarts
B . continue to operate as if the system were in operation
C . remain open until evaporator pressure equalizes, then close until the compressor restarts
D . always be completely closed until the compressor restart
-
The primary function of a fuel delivery check valve assembly is to（）
A . deliver proper fuel quantity to the injection nozzle
B . provide rapid fuel injection cutoff
C . control fuel quantity entering the pump body
D . control fuel pressure delivered to the combustion chamber
-
The valve best suited for throttling gas or liquid flow in a pipeline is the（）.
A . gate valve
B . globe valve
C . check valve
D . plug cock
-
Australia is almost as big as the US, but has a smaller population.
-
When the air in a certain space is squeezed to occupy a smaller space, the air is said to be ______.
A．commenced
B．compressed
C．compromised
D．compensated
-
When a refrigeration compressor is in the ‘off’ cycle, the thermal expansion valve will .
A.always be wide open when the compressor restarts
B.continue to operate as if the system were in operation
C.remain open until evaporator pressure equalizes, then close until the compressor restarts
D.always be completely closed until the compressor restarts
-
When the relief valve is used as a constant pressure valve, it is connected to the outlet of the hydraulic pump to ensure that the outlet pressure of the hydraulic system (pump) is constant.
A:正确;
B:错误
-
Router R1 learns two routes with BGP for prefix 200.1.0.0/16. Comparing the two routes, route 1 has a shorter AS_Path Length, smaller MED, the same Weight, and smaller Local PreferencE.Which of the following is true about Router R1‘s choice of best path for this prefix？（）
A. Route 1 is the best route.
B. Route 2 is the best route.
C. The routes tie as best, but one will be picked to be placed in the routing table based on tiebreakers .
D. Neither route is considered best.
