12．滑油箱(图8-4)通常安装在发动机上，虽然它可以作为外部齿轮箱的一个整体构件，但一般是一个单独的装置。它应当带有能使润滑系统放油和加油的设备。还应当备有观察窗或者量杆，用来对滑油采统的油量进行检查。加油器可以是重力式的，也可以是压力加油式的。在某些发动机上，这两种形式兼备。对于设计上要作倒飞的飞机，还要有能提供连续供油的设备。由于在轴承腔中，空气和滑油混在一起，所以油箱内还有油气分离装置，将回油
中的空气除掉。
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
图8-4 一种滑油箱
Fig. 8-4 An oil tank.
17．由于少量不可压缩的滑油滞留在齿轮啮合处，它可能产生液压堵塞，并可能导致油泵损坏，所有在泵体的端面上加工一道减压槽，作为滑油泄出的流路。
18．齿轮泵可同时用作增压油泵(供油)和回油泵(回油)，两者处于同一壳体之内。这种滑油泵组由附件驱动系统驱动(第7章)。
19．一次压射式油泵(图8-6)在其油缸中装有一定量的滑油。当活塞受压顺着油缸筒往上运动时．在油门装置的控制下，滑油迫使出口活门打开，使一股滑油流向需要润滑的零件。当活塞到达油缸筒的顶
部时，出口活门由于油压减低而关闭。滑油泵油缸
的重新装油是靠一根弹簧迫使活塞回到它原先的位置来实现的。因为活塞的移动减低了油缸和油箱之间的压力，使进油活门打开，直到油缸重新充满为止。
20.大多数普通的滑油分配装置是单孔式的，它将定量的滑油引向润滑对象。这些喷油孔安排在离对象尽可能近的地方，以克服局部环境的紊乱使滑油射流偏斜的可能性。喷油孔的最小直径为0.04英寸，当工作在40磅／平方英寸的压力下时，可通过的流量为每小时l2加仑。如果需要，可在上游使用限流器以减少流量。
15．齿轮式油泵通常用于循环式滑油系统，但有些发动机也用旋板式和常压油泵。一次压射式油泵(第19段)由于简单，使其用于短时间工作并采用总损耗滑油系统的发动机中是非常理想的。
16．齿轮泵(图8-5)由一对相互啮合的铜齿轮构成，它们装在精密配合铝合金壳体之内。当两齿轮旋转时，滑油被吸入油泵，在齿和泵体之间流过，在出口处向外供油。
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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