Differentials: Other Land Rover Freelander I рестайлинг

INTERMEDIATE REDUCTION DRIVE

The Intermediate Reduction Drive (IRD) is attached to the JATCO automatic transmission in place of a conventional transfer case. (Scheme 51) In conjunction with the automatic transmission, it provides drive to the front and rear wheels. The IRD incorporates a differential unit to control the proportion of drive delivered to each front wheel. In addition, it operates in conjunction with the viscous coupling to give the vehicle a self-sensing 4WD system. The main casing, cover and pinion housing are manufactured from cast aluminum.

The unit consists of a main casing, a right housing, primary shaft, an intermediate shaft, a differential unit, a lay gear, hypoid gear set, a rear output pinion and a pinion housing. An oil cooler, connected to the engine coolant system, is installed to prevent overheating of IRD lubricating fluid. The main casing also incorporates the oil filler/level and drain plugs and a breather outlet. There are a total of 7 taper roller bearings and one parallel roller bearing supporting the primary shaft, differential and output shaft assemblies.

Externally, 3 oil seals prevent lubricating oil escaping from the transmission and the IRD unit. The transmission gear case houses the oil seal for the left hand front axle shaft, and the right housing on the IRD unit houses the oil seal for the right hand front axle shaft, with the remaining oil seal located in the pinion housing of IRD.

There are also 4 internal oil seals in the IRD unit. There are 2 smaller diameter oil seals installed internally at each end of primary shaft. These prevent oil ingress along the intermediate shaft from the IRD unit at the differential end. At the opposite end, the seal prevents oil ingress from the transmission along the intermediate shaft. There are 2 larger oil seals installed in the main casing where IRD unit enters the transmission. The inner oil seal prevents oil ingress from the IRD primary shaft entering into the area between the 2 seals, and the outer oil seal prevents oil ingress from the transmission entering the same area.

On the underside of the main casing is a "tell-tale" drilling which is positioned between the inner and outer primary shaft oil seals. Oil leakage from the drilling will indicate either a faulty inner or outer primary shaft oil seal. An "O" ring seal, installed in a machined groove, seals IRD main casing to transmission housing.

The unit is comprised of a main casing, a right housing, a primary shaft, an intermediate shaft, a differential unit, a laygear, hypoid gear set, a rear output pinion and a pinion housing.

Scheme 51

Intermediate Reduction Drive (IRD) Oil Seals

Externally, 3 oil seals prevent lubricating oil escaping from the transmission and the IRD unit. The transmission gear case houses the oil seal for left hand front axle shaft. The right housing on IRD unit houses oil seal for right hand front axle shaft, with remaining oil seal located in IRD pinion housing.

There are 4 internal oil seals in the IRD unit. The 2 smaller diameter oil seals are installed internally at each end of the primary shaft. (Scheme 52) These prevent oil ingress along intermediate shaft from IRD unit at the differential end. At the opposite end, the seal prevents oil ingress from transmission along intermediate shaft. The 2 larger oil seals are installed in the main casing where the IRD unit enters transmission. The inner oil seal prevents oil ingress from IRD primary shaft entering into area between the 2 seals. The outer oil seal prevents oil ingress from the transmission entering the same area.

On the underside of the main casing is a "tell-tale" drilling which is positioned between inner and outer primary shaft oil seals. Oil leakage from the drilling will indicate either a faulty inner or outer primary shaft oil seal. An "O" ring seal, installed in a machined groove, seals IRD main casing to transmission housing.

Scheme 52

REAR DIFFERENTIAL

The rear differential assembly serves to convert the "angle of drive" through 90 degrees and distribute drive, in the desired proportions, to both rear wheels. (Scheme 51) The type of rear differential installed is an integral carrier housing hypoid-gear in which the center line of the drive pinion is mounted below the center line of the ring gear. To minimize weight, the differential housing is manufactured in aluminum alloy. The assembly is secured to the rear subframe by 3 mounts with rubber bushings.

The differential housing incorporates the drive pinion gear shaft, which is supported by 2 opposed taper roller bearings installed to the pinion and cups assembled into the carrier housing. The pinion bearing preload is controlled by a collapsible spacer and the torque of the pinion nut. The pinion position is controlled by a selective shim located between the inner pinion bearing cone and the pinon gear head.

The differential is supported by 2 opposed taper roller bearings. The bearing cups are secured in the housing by removable bearing caps. Shims are located between the differential bearing cones and differential case for controlling differential bearing preload and ring gear to pinion gear backlash.

The differential casing rear cover is manufactured from pressed steel and is sealed to the casing with RTV silicone sealant. The cover also incorporates the oil filler plug. A breather is located in the top of the differential casing to prevent pressurization of the casing.

The pinion oil seal, which is installed in the differential casing is referred to as a "labyrinth" type seal and is especially designed to prevent contaminant ingress. The oil seal works in conjunction with a pressed steel shield, referred to as an "oil slinger" which is pressed onto the pinion drive flange. The 2 axle shafts are also sealed by "labyrinth" type oil seals installed in the differential housing.

The differential oil level should be maintained to the bottom of the filler plug. No oil changes are specified unless contamination is suspected.

Drive is transmitted from the transmission to Intermediate Reduction Drive (IRD) primary shaft via the splined hub in the transmission final drive gear carrier. (Scheme 53) The drive is then transmitted from the primary shaft gear, which is integral with the primary shaft, to the laygear which in turn drives the differential for the front axle shafts, and via a bevel drive gear and pinion to drive the rear axle. The intermediate shaft passes through the center of the IRD primary shaft, and is the drive link between the IRD differential, and the left-hand front axle shaft, passing through the center of the final drive carrier.

Scheme 53

Intermediate Reduction Drive (IRD)

1. Remove underbelly panel. See «UNDERBELLY PANEL»(ref-165921-S18267577202004090800000) under REMOVAL & INSTALLATION. Place container under IRD unit. Clean area around filler/level and drain plugs.
2. Using wrench LRT-41-021, remove filler plug and discard sealing washer. (Scheme 54) Remove drain plug, discard sealing washer and allow oil to drain. Install NEW sealing washer and tighten drain plug to specification. See «TORQUE SPECIFICATIONS»(ref-165921-S04959808072004090800000).
3. Fill with fluid until it just runs from filler/level hole. Allow sufficient time for fluid to flow and reach a common level in unit. Install NEW sealing washer and tighten filler/level plug to specification. See «TORQUE SPECIFICATIONS»(ref-165921-S04959808072004090800000). Install underbelly panel. See «UNDERBELLY PANEL»(ref-165921-S18267577202004090800000) under REMOVAL & INSTALLATION.

Scheme 54

1. With vehicle on a ramp at a convenient working height, carefully remove rear differential level plug. Check oil level. Before topping up oil level, check for visible signs of leakage.
2. Pay particular attention to axle shaft oil seals, differential pinion oil seal and backplate gasket. Refit level plug to rear differential and tighten to specification. See «TORQUE SPECIFICATIONS»(ref-165921-S04959808072004090800000) .

DISCONNECTING & CONNECTING BATTERY

Before disconnecting battery, disable alarm system and switch off all electrical equipment. If the radio is to be serviced, ensure the security code has been deactivated.