3239209 - Introduction - MANUAL GEARBOX AND DIFFERENTIAL

DESCRIPTION

Gearbox structure

The structure of the gearbox consists of:

• gearbox casing which contains and supports the main and layshafts, rods and gear selector forks and the gear selector and engagement device.
• a rear cover which contains the 5^th speed gears, the 5^th speed engagement fork and the rear bearing retaining plate for the main and layshafts
• the bell housing which contains the clutch and the coaxial clutch control

1, Main shaft 2, 5 ^th speed drive gear 3, 4 ^th speed drive gear 4, 3 ^rd speed drive gear 5, 2 ^nd speed drive gear 6, 1 ^st speed drive gear 7, Reverse speed drive gear 8, Layshaft 9, Planet gears 10, Planet gears 11, Ring gear 12, Mileometer reverse idler gear 13, Gear casing 14, Clutch casing 15, Differential mount casing 16, Gear casing cover 17, Clutch coaxial control device

Main shaft

The main shaft consists of:

• 1^st , Reverse and 2^nd speed gears
• 3^rd , 4^th , 5^th speed gears, fitted on needle bearings with the synchronizers

3 rd , 4 th and 5 th speed gears fitted on the shaft make it possible to:

• reduce shift loads during synchronisation
• reduce gearbox noise while in neutral.

The main shaft is supported by means of two ball bearings.The coaxial cluth control device is fitted to the end of the clutch shaft (see 18 T. SPARK)

Layshaft

The layshaft consists of:

• 1^st and 2^nd speed gears, fitted on needle bearings with synchronizers
• 3^rd , 4^th and 5^th speed gears fitted on the shaft.

The layshaft is supported on:

• a roller bearing at the pinion end
• a ball bearing at the cover end.

Gears

The gears are the following type:

• helical toothed for the forward speeds
• straight toothed for Reverse.

Synchronizers

The synchronizers for all the gears are brass, baulk ring, single-cone "Borg-Warner" type

Gear shift/selection system

The gear shift/selection system consists of:

• a swinging control (1) connected to selector dog (2)
• selector dog (2) which operates sliding rods (4) fitted with synchronisation sleeve control forks (3, 5, 6, 7).

1, Fluctuating control 2, Selector dog 3, 1 ^st and 2 ^{nd engagement/selector fork} 4, Sliding rods 5, 5 ^{th engagement/selector fork} 6, 3 ^rd and 4 ^{th engagement/selector fork} 7, Reverse engagement/selector fork

Safety devices

The safety devices consist of:

• three dowels (1) that prevent two speeds being engaged at the same time
• dowel (3), pin (4) and spring (5), which maintain reversing dog (2) in a safe position to prevent dangerous movements of revesing fork (9) with the attendant possibility of engaging reverse.
• Lever (10) and spring (11), which prevent involuntary engagement of revese while changing from 5^th to 4^th speed.

1, Safety dowels 2, Reverse dog 3, Dowel 4, Pin 5, Spring 6, 5 ^th and Reverse rod 7, 3 ^rd and 4 ^{th rod} 8, 1 ^st and 2 ^{nd rod} 9, Reverse selector fork 10, Lever 11, Spring

Differential

The differential consists of:

• a crown wheel and pinion reduction
• a differential housing constructed in a single piece which includes the differential and planet gears.

The differential housing is supported by two conical bearings and the ring gear is fixed by bolts.The drive gear for the speedometer is fitted on the outside of the differential housing.