Page 83 - The Jet Engine

8: Lubrication

Contents Page

Introduction 73
Lubricating systems 73

Pressure relief valve system
Full flow system
Total loss (expendable) system
Oil system components 77

Lubricating oils 83

2. The requirements of a turbo-propeller engine are
somewhat different to any other types of aero gas
turbine. This is due to the additional lubrication of the
heavily loaded propeller reduction gears and the
need for a high pressure oil supply to operate the
propeller pitch control mechanism.

3. Most gas turbine engines use a self-contained
recirculatory lubrication system in which the oil is
distributed around the engine and returned to the oil
tank by pumps. However, some engines use a
system known as the total loss or expendable system
in which the oil is spilled overboard after the engine
has been lubricated.
INTRODUCTION
LUBRICATING SYSTEMS
1. The lubrication system is required to provide
lubrication and cooling for all gears, bearings and 4. There are two basic recirculatory systems,
splines. It must also be capable of collecting foreign known as the 'pressure relief valve1 system and the
matter which, if left in a bearing housing or gearbox, 'full flow' system. The major difference between them
can cause rapid failure. Additionally, the oil must is in the control of the oil flow to the bearings. In both
protect the lubricated components which are manu- systems the temperature and pressure of the oil are
factured from non-corrosion resistant materials. The critical to the correct and safe running of the engine.
oil must accomplish these tasks without significant Provision is therefore made for these parameters to
deterioration. be indicated in the cockpit.

73