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.每一種表的電路都類似。滑油壓力作用在傳感器上，引起輸入到指示器的電流發生變化。變化的大小與施加在傳感器上的壓力成正比。
37.滑油壓力由電傳遞到儀表板上的指示器。有裝置采用標志式指示器，它指示究竟壓力是高、正常、或低。另一些裝置采用盤式表，按磅/平方英寸加以標定。
39.傳感器可以是直接壓力式，也可以是壓差式。后者感受發動機進油和回油滑油壓力之間的壓差。滑油回油由軸承處的冷卻和封嚴空氣（第9章） 壓。
40．除了傳感器帶動的壓力表之外，還有一個滑油低壓警告開關，用以指示為保證發動機繼續安全運轉而能夠提供的最低滑油壓力。開關與駕駛艙中的一個警告燈相連，當滑油壓力降低到可接受的最小值以下時，燈就亮起來。
燃油溫度和壓力
41.低壓燃油的供油溫度和壓力由電傳遞到它們各
自的指示器，這些指示顯示低壓系統是否正在提供足夠的燃油且沒有氣穴，以及溫度是否適合于工作。燃油溫度和壓力指示器與滑油溫度和壓力指示器相似。
42．在某些發動機上在低壓燃油濾中裝有燃油壓差開關。它感測油濾元件前后的壓差。該開關與警告燈相連，發出油濾部分堵塞的指示，這時可能發生缺油。
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．雖然在同一型別的不同發動機之間，在一次規定的飛行中所消耗的燃油量會略有不同，但是對于發動機順利工作和測定飛行中正在消耗的燃油量來說，燃油流量確實能提供一種很有用的指示。一個典型的系統包括：裝在低壓燃油系統中的燃油流量傳感器和顯示以每小時加侖、磅或公斤為單位的燃油流量與總耗油量的指示器(圖12-10)。傳感器由電感測燃油流量并由相聯的電子裝置向指示器發送與燃油流量成正比的信號。
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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