12．滑油箱(圖8-4)通常安裝在發(fā)動機上，雖然它可以作為外部齒輪箱的一個整體構(gòu)件，但一般是一個單獨的裝置。它應(yīng)當(dāng)帶有能使?jié)櫥到y(tǒng)放油和加油的設(shè)備。還應(yīng)當(dāng)備有觀察窗或者量桿，用來對滑油采統(tǒng)的油量進(jìn)行檢查。加油器可以是重力式的，也可以是壓力加油式的。在某些發(fā)動機上，這兩種形式兼?zhèn)�。對于設(shè)計上要作倒飛的飛機，還要有能提供連續(xù)供油的設(shè)備。由于在軸承腔中，空氣和滑油混在一起，所以油箱內(nèi)還有油氣分離裝置，將回油
中的空氣除掉。
second shot to be delivered to the rear bearing only, after a predetermined period.
11. After lubricating the fuel unit and front bearings, the oil from the front bearing drains into a collector tray and is then ejected into the main gas stream through an ejector nozzle. The oil that has passed through the rear bearing, drains into a reservoir at the rear of the bearing where it is retained by centrifugal force until the engine is shut down. This
Lubrication
oil then drains overboard through a central tube in the exhaust unit inner cone.
OIL SYSTEM COMPONENTS
12. The oil tank (fig. 8-4) is usually mounted on the engine and is normally a separate unit although it may also be an integral part of the external gearbox. It must have provision to allow the lubrication system to be drained and replenished. A sight glass or a dipstick must also be incorporated to allow the oil
圖8-4 一種滑油箱
Fig. 8-4 An oil tank.
17．由于少量不可壓縮的滑油滯留在齒輪嚙合處，它可能產(chǎn)生液壓堵塞，并可能導(dǎo)致油泵損壞，所有在泵體的端面上加工一道減壓槽，作為滑油泄出的流路。
18．齒輪泵可同時用作增壓油泵(供油)和回油泵(回油)，兩者處于同一殼體之內(nèi)。這種滑油泵組由附件驅(qū)動系統(tǒng)驅(qū)動(第7章)。
19．一次壓射式油泵(圖8-6)在其油缸中裝有一定量的滑油。當(dāng)活塞受壓順著油缸筒往上運動時．在油門裝置的控制下，滑油迫使出口活門打開，使一股滑油流向需要潤滑的零件。當(dāng)活塞到達(dá)油缸筒的頂
部時，出口活門由于油壓減低而關(guān)閉�；捅糜透�
的重新裝油是靠一根彈簧迫使活塞回到它原先的位置來實現(xiàn)的。因為活塞的移動減低了油缸和油箱之間的壓力，使進(jìn)油活門打開，直到油缸重新充滿為止。
20.大多數(shù)普通的滑油分配裝置是單孔式的，它將定量的滑油引向潤滑對象。這些噴油孔安排在離對象盡可能近的地方，以克服局部環(huán)境的紊亂使滑油射流偏斜的可能性。噴油孔的最小直徑為0.04英寸，當(dāng)工作在40磅／平方英寸的壓力下時，可通過的流量為每小時l2加侖。如果需要，可在上游使用限流器以減少流量。
15．齒輪式油泵通常用于循環(huán)式滑油系統(tǒng)，但有些發(fā)動機也用旋板式和常壓油泵。一次壓射式油泵(第19段)由于簡單，使其用于短時間工作并采用總損耗滑油系統(tǒng)的發(fā)動機中是非常理想的。
16．齒輪泵(圖8-5)由一對相互嚙合的銅齒輪構(gòu)成，它們裝在精密配合鋁合金殼體之內(nèi)。當(dāng)兩齒輪旋轉(zhuǎn)時，滑油被吸入油泵，在齒和泵體之間流過，在出口處向外供油。
Lubrication
system contents to be checked. The filler can be either the gravity or pressure filling type; on some engines both types are fitted. Provision is also made for a continuous supply of oil to be made available in aircraft which are designed to operate during inverted flight conditions. Since air is mixed with the oil in the bearing chambers, a de-aerating device is incorporated within the oil tank which removes the air from the returning oil.
13.
The oil pumps are vital to the efficient operation of the engine. Failure of the pumps will necessitate a rapid shutdown of the engine. For this reason, the oil pump driveshafts do not incorporate a weak shear-neck (Part 7) because they must continue to supply oil for as long as possible, regardless of damage.
14.
As the feed oil is distributed to all the lubricated parts of the engine a substantial amount of sealing air (Part 9) mixes with it and increases its volume. Additionally the bearing chambers operate under differing pressures. Therefore, to prevent flooding it is usually necessary to have $. scavenge pump for each chamber.
15.
Gear type pumps are normally used in recircu-latory oil systems but vane and gerotor pumps are employed in some engines. The simplicity of single-shot pumps (para. 19) make them ideal for engines which run for a short duration and use the total loss type of oil system.
16.
Gear pumps (fig. 8-5) consist of a pair of inter-meshing steel gears which are housed in a close fitting aluminium casing. When the gears are rotated, oil is drawn into the pump, carried round between the teeth and casing and delivered at the outlet.
17.
Since a small quantity of incompressible oil becomes trapped in the gear mesh, which can cause a hydraulic lock and possible pump damage, a relief slot is machined into the end faces of the casing to provide an escape route for the oil.
18.
Gear pumps are used both as pressure (feed) pumps and scavenge (return) pumps and are incor-porated within a common casing. The oil pumps pack is driven by the accessory drive system (Part 7).
19.
Single-shot pumps (fig. 8-6) have a quantity of oil contained within a cylinder. When the piston is forced up the cylinder bore, under the control of the throttle unit, the oil forces the outlet valves to open allowing a flow of oil to the parts required to be lubricated. When the piston reaches the top of the cylinder bore the outlet valves close due to the reduced oil pressure. Recharging of the oil pump
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