33.
The output to the temperature control system can also be used to provide a signal, in the form of short pulses, which, when coupled to an indicator, will digitally record the life of the engine. During engine operation in the higher temperature ranges, the pulse frequency increases progressively causing the cyclic-type indicator to record at a higher rate, thus relating engine or unit life directly to operating temperatures.
34.
Thermocouples may also be positioned to transmit a signal of air intake temperature into the exhaust gas temperature indicating and control systems, thus giving a reading of gas temperature that is compensated for variations of intake temperature. A typical double-element thermocouple system with air intake probes is shown in fig. 12-8.
Oil temperature and pressure
35.
It is essential for correct and safe operation of the engine that accurate indication is obtained of both the temperature and pressure of the oil. Temperature and pressure transmitters and indicators are illustrated in fig 12-9.
36.
Oil temperature is sensed by a temperature-sensitive element fitted in the oil system. A change in temperature causes a change in the resistance value and, consequently, a corresponding change in the current flow at the indicator. The indicator pointer is deflected by an amount equivalent to the temperature change and this is recorded on the gauge in degrees centigrade.
37.
Oil pressure is electrically transmitted to an indicator on the instrument panel. Some installations use a flag-type indicator, which indicates if the pressure is high, normal or low; others use a dial-type gauge calibrated in pounds per square inch (p.s.i.).
38.
Electrical operation of each type is similar; oil pressure, acting on the transmitter, causes a change in the electric current supplied to the indicator. The amount of change is proportional to the pressure applied at the transmitter.
39.
The transmitter may be of either the direct or the differential pressure type. The latter senses the pressure difference between engine feed and return
38.每一种表的电路都类似。滑油压力作用在传感器上，引起输入到指示器的电流发生变化。变化的大小与施加在传感器上的压力成正比。
37.滑油压力由电传递到仪表板上的指示器。有装置采用标志式指示器，它指示究竟压力是高、正常、或低。另一些装置采用盘式表，按磅/平方英寸加以标定。
39.传感器可以是直接压力式，也可以是压差式。后者感受发动机进油和回油滑油压力之间的压差。滑油回油由轴承处的冷却和封严空气（第9章） 压。
40．除了传感器带动的压力表之外，还有一个滑油低压警告开关，用以指示为保证发动机继续安全运转而能够提供的最低滑油压力。开关与驾驶舱中的一个警告灯相连，当滑油压力降低到可接受的最小值以下时，灯就亮起来。
燃油温度和压力
41.低压燃油的供油温度和压力由电传递到它们各
自的指示器，这些指示显示低压系统是否正在提供足够的燃油且没有气穴，以及温度是否适合于工作。燃油温度和压力指示器与滑油温度和压力指示器相似。
42．在某些发动机上在低压燃油滤中装有燃油压差开关。它感测油滤元件前后的压差。该开关与警告灯相连，发出油滤部分堵塞的指示，这时可能发生缺油。
Controls and instrumentation
oil pressures, the return oil being pressurized by cooling and sealing air (Part 9) from the bearings.
40. In addition to a pressure gauge operated by a transmitter, an oil low pressure warning switch may be provided to indicate that a minimum pressure is available for continued safe running of the engine. The switch is connected to a warning lamp in the flight compartment and the lamp illuminates if the pressure falls below an acceptable minimum.
Fuel temperature and pressure
41. The temperature and pressure of the low pressure fuel supply are electrically transmitted to their respective indicators and these show if the low pressure system is providing an adequate supply of fuel without cavitation and at a temperature to suit the operating conditions. The fuel temperature and 燃油流量
43．虽然在同一型别的不同发动机之间，在一次规定的飞行中所消耗的燃油量会略有不同，但是对于发动机顺利工作和测定飞行中正在消耗的燃油量来说，燃油流量确实能提供一种很有用的指示。一个典型的系统包括：装在低压燃油系统中的燃油流量传感器和显示以每小时加仑、磅或公斤为单位的燃油流量与总耗油量的指示器(图12-10)。传感器由电感测燃油流量并由相联的电子装置向指示器发送与燃油流量成正比的信号。
pressure indicators are similar to those for temperature and pressure indication.
42. On some engines, a fuel differential pressure switch, fitted to the low pressure fuel filter, senses the pressure difference across the filter element. The switch is connected to a warning lamp that provides indication of partial filter blockage, with the possibility of fuel starvation.
Fuel flow
43. Although the amount of fuel consumed during a given flight may vary slightly between engines of the same type, fuel flow does provide a useful indication of the satisfactory operation of the engine and of the amount of fuel being consumed during the flight. A typical system consists of a fuel flow transmitter, which is fitted into the low pressure fuel system, and an indicator, which shows the rate of fuel flow and the
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