Power Transmission; Wheels And Tyres; Propeller Shaft; Rear Axle - Volvo 121 Servicing

DESCRIPTION

Power transmission

Clutch
The function of the clutch is to transmit the power from the engine to
the gearbox. The clutch is of the single dry plate type with diaphragm
spring. The diaphragm spring 'functions partly as a lever when declutch-
ing and partly as a pressure spring when engaging.
Gearbox
The gearbox is used to regulate the speed ratio between the engine and the
rear axle so that the engine always operates in its most favourable speed
range. The gearbox is synchronised on all the forward gears; this means
that gear-changing can be carried out without double declutching. Since
the gearbox is fitted with helical gears and the gear lever is rubber in-
sulated, excellent sound insulation is obtained. See page 57 for data.

Propeller shaft

The propeller shaft, which is the connecting link between the gearbox
and the rear axle, is divided into two sections. The forward section is
journalled at its rear end in a bearing housing suspended in a rubberized
ring.

Rear axle

The driving power of the engine is transmitted from the propeller shaft
to the rear wheels through the rear axle. The rear axle is of the hypoid
type, i.e. drive pinion is below the centre line of the drive shafts. See
page 57 for data.
Brakes
The vehicle is equipped with disc brakes at the front and drum brakes
at the rear as standard. The brake system is also provided with a re-
ducer valve, which prevents involuntary locking of the rear wheels.
The footbrake system is hydraulic and influences all four wheels. The
hydraulic system consists of a 'fluid-filled master cylinder which, when
the brake pedal is depressed, transmits the brake pressure through the
brake fluid in the lines to the wheel unit cylinders. The plungers in these
are then pressed outwards and apply the brake shoes or brake pads res-
pectivly.
Vehicles fitted with the B 18 D engine are also provided with vacuum
type servo brake cylinders.
The handbrake system operates mechanically on the rear wheels.

Wheels and tyres

The vehicle has pressed steel wheels with lugs for the attachment of the
hub caps. All wheels are carefully balanced and the tyres are of the tube-
less type.
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