【名词&注释】
稳定性(stability)、PGA调速器(pga governor)、具体情况(concrete conditions)
[单选题]液压装置油温在( )℃以下，不允许启动。
A. -10
B. O
C. 10
D. 20
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举一反三：
[单选题]第二组：Magnetic pickup (MPU) sensors are devices which can be used in conjunction with electronic control modules for monitoring of parameters such as speed, direction of rotation and a variety of alarm conditions. MPU sensors are available in various sizes and types. Following are some guidelines for their selection on industrial engines. MPUs are located near a flywheel, camshaft or other type of gear with rotation relative to engine speed. The passing of the gear teeth through the MPU tip (pole) generates a voltage and frequency. This frequency is converted to a speed reference by a control module. It should be noted here that most MPUs will develop similar signals. However, the magnitude and strength of the signal is dependent on the size of the sensor in relation to the gear teeth, the clearance between the pole piece and the gear teeth, and various other factors. As a general rule of thumb, the following standards should be met:①Dimension of tooth top surface should be equal to or more than the pole piece diameter.
A. ②Tooth height should be equal to, or more than the space between teeth.
B. ③The space between teeth should be approximately three times the pole piece diameter.
C. ④Air gap (clearance) between tooth and pole piece should be between 0.015" to 0.030". MPUs
D. normally have 3/8", 5/8" threads and 2", 3" and 4" lengths. Determining which size is appropriate
E. depends on the space available for installation, the availability of pre-drilled holes and consideration to
F. those rules mentioned above. In most cases, these will be the only factors affecting the selcetion of a
G. MPU.
H. MPUs can be used to ____.①sense speed ②supply alarm ③sense direction of rotation.
I. ①②
J. ②③
K. ①③
L. ①②③
[单选题]环槽磨损后依具体情况不同可分别采用______等方法进行修复。Ⅰ.修理尺寸法；Ⅱ.光车＋镀铁；Ⅲ.恢复尺寸法；Ⅳ.换新活塞；Ⅴ.光车＋镀铬。
A. Ⅰ＋Ⅱ＋Ⅳ
B. Ⅰ＋Ⅳ
C. Ⅰ＋Ⅲ＋Ⅳ
D. Ⅰ＋Ⅲ
[单选题]应及早采取行动，以避免紧迫局面的形成是________。
A. 让路船的责任
B. 直航船的责任
C. 让路船和直航船共同的责任
D. 当让路船不履行时，由直航船履行
[单选题]下述关于WoodwardPGA调速器结构特点中错误的是( )。
A. 采用刚性反馈机构保证具有一定的稳定调速率
B. 稳定调速率的调节范围通常是0%～12%，可打开端盖进行调节
C. 在稳定调速率的调节中决不允许出现负稳定调速率的调节
D. 稳定性调节机构是用来调节补偿针阀开度与反馈指针刻度
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