Discovery 2. Manual - part 112

 

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Discovery 2. Manual - part 112

 

 

MANUAL GEARBOX - R380

DESCRIPTION AND OPERATION

37-5

3rd/4th gear selector fork             
Interlock spool 
1st/2nd gear selector fork
Selector shaft yoke pins
Selector shaft
Reverse/5th gear selector fork
Selector yoke
Setscrew
Input shaft front taper bearing 

10 Input shaft 
11  4th gear synchromesh ring
12 Pilot taper bearing
13 Spacer
14 3rd/4th gear synchromesh hub and sleeve
15 3rd gear synchromesh rings
16 3rd gear
17 Needle roller bearings
18 Output shaft
19 Roll pin
20 Needle bearing
21 2nd gear
22 2nd gear synchromesh rings
23 2nd/1st gear synchromesh hub and sleeve
24 1st gear synchromesh rings
25 1st gear 
26 Needle roller bearing
27 Bush
28 Output shaft taper bearing 

29 Selective shim
30 Selective washer
31 Bush
32 Needle roller bearing 
33 Reverse gear
34 Reverse gear synchromesh ring 
35 Reverse/5th gear synchromesh hub and sleeve
36 Circlip
37 Needle roller bearings
38 5th gear synchromesh ring
39 5th gear 
40 5th gear segments
41 5th gear segment retaining ring            
42 Output shaft rear support bearing
43 Layshaft support bearing
44 Layshaft
45 Layshaft support bearing
46 Selective shim 
47 Layshaft reverse gear
48 Layshaft 5th gear
49 Split collar
50 5th gear nut
51 Layshaft rear support bearing 
52 Spacer
53 Reverse idler gear
54 Needle roller bearing
55 Reverse idler shaft

MANUAL GEARBOX - R380

37-6

DESCRIPTION AND OPERATION

R380 gearbox cross section

Input shaft
Breather
Input shaft 4th gear
Selector shaft
3rd/4th selector fork
Output shaft 3rd gear
Output shaft 2nd gear
1st/2nd selector fork
Output shaft 1st gear

10 Selective shims - output shaft and layshaft end-

float

11 Selective shim - reverse gear idler shaft end-

float

12 5th/reverse selector fork
13 Selector yoke

14 Gear change assembly
15 Railko bush
16 Output shaft 5th gear
17 Output shaft oil seal
18 Output shaft
19 Oil pump
20 5th/reverse gear synchromesh assembly
21 Output shaft reverse gear
22 Centre plate
23 Oil filter
24 1st/2nd synchromesh assembly
25 Layshaft
26 3rd/4th gear synchromesh assembly
27 Input shaft oil seal

MANUAL GEARBOX - R380

DESCRIPTION AND OPERATION

37-7

Description

General
The R380 all synchromesh gearbox has five forward speeds and reverse and is mounted in line with the engine. The 
clutch bell housing  is bolted to the front of the gearbox and the transfer box is mounted at the rear.

Gearbox casings
Gearbox casings consist of a front cover, gearcase, centre plate and extension housing. All casings with the exception 
of the front cover are located to each other by dowels and sealed. Gearbox filler/level and drain plugs are located in 
the gearcase. 

Reverse lamp switch
 A reverse lamp switch is inserted into the extension housing. Selection of reverse gear will close the switch allowing 
current from fuse 25 to flow through the switch to illuminate the reverse lamps. The switch also provides a feed to the 
BCU and the electrochromic automatic interior mirror - if fitted; the mirror moving from the dimmed position if 
applicable.

Gearchange assembly
The gearchange assembly is bolted to the top of the gearcase, the upper gear lever being attached to the lower gear 
lever by means of a clamp bolt. The lower gear lever ball is housed in a Railko bush inserted in the gear change 
housing, the end of the lever locating in the selector yoke which is attached to the end of the selector shaft. Bias 
springs provide a positive return of the gear lever to the neutral position with selection of 1st/2nd and 5th/reverse gears 
being against bias spring pressure. Spring loaded detent balls fitted in the centre plate locate in grooves in the selector 
shaft to provide positive gear and neutral selection.

Lubrication
Lubrication is by an oil pump located in the extension housing and driven by the layshaft with additional lubrication 
being provided by splash. The pump directs oil via a filter and internal drillings in the output shaft to lubricate the 
components. On non UK and non European models, provision for oil cooling is by means of a thermostat housed in 
a cover bolted to the side of the extension housing. The cover incorporates tappings for connections to an oil cooler. 
On UK and European models, the thermostat and cover are replaced by an oil by-pass block.

Internal pressures produced within the gearbox are vented to atmosphere via a plastic breather pipe. The pipe is 
attached to the extension housing and is routed across the top of the gearcase and secured at the open end by a clip 
attached to the engine cylinder block.

Selector shaft and forks
Selector forks for 1st/2nd, 3rd/4th and 5th/reverse gears are located on a single selector shaft; the 1st/2nd and 3rd/
4th selector forks are inside the main gearcase whilst the 5th/reverse selector fork is inside the extension housing. 
Each of the selector forks locates inside its corresponding synchromesh hub.

Synchromesh assemblies
Each synchromesh assembly is located on the output shaft adjacent to its corresponding gears and comprises a 
synchromesh ring, hub, slippers and sleeve. The hubs and slippers are retained in the sleeves by means of spring 
clips. 1st/2nd and 3rd synchromesh assemblies are fitted with double synchromesh rings whilst 4th, 5th and reverse 
assemblies are fitted with single rings.

The gear train
The gear train comprises an input shaft, output shaft, layshaft and reverse idler shaft together with their appropriate 
gears and synchromesh assemblies.

The gear train input shaft, output shaft and layshaft are supported by taper roller bearings with all gears on the input 
and output shafts running on caged needle roller bearings. Layshaft gears are integral with the shaft with the 
exception of reverse/5th gears which are splined to the shaft and retained with a nut. 1st, 2nd, 3rd and 4th gears are 
shot peened to improve durability. The reverse idler shaft and gear are supported in the centre plate by a caged 
needle roller bearing. End-float of the output shaft and layshaft is controlled by selective shims located in the centre 
plate whilst reverse idler shaft end-float is controlled by a selective shim located behind reverse gear.

MANUAL GEARBOX - R380

37-8

DESCRIPTION AND OPERATION

Operation

Drive is transmitted from the crankshaft, through the clutch to the gearbox input shaft which transmits drive via the 
layshaft to the output shaft in all gears with the exception of 4th gear which provides a direct drive from the input shaft 
to the output shaft. Drive from the gearbox output shaft is transmitted to the transfer box input shaft via a flange splined 
to the output shaft.

 

 

 

 

 

 

 

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