Manual Gearboxes / Transmissions
Manual Transmsission, how it works?
A Manual Transmission provides a range of forward gears to be selected, according to opposing forces and desired economy. It also offers a means of reversing the vehicle, and a neutral position providing a permanent break in transmission.
To reduce the skill required by the driver to produce a quick, quiet gear-change, synchromesh units were devised which aimed at synchronising the two halves of gear engagement dog clutches, before the dog teeth made contact, by the use of cone clutches.
Some transmissions can also provide a power take off (PTO) point.
Synchromesh Unit, how it works?
The Synchromesh unit it the part of the manual transmission that allows the driver to make seamless gear changes, without the "grinding" that you would associate with older gear boxes.
Synchromesh units were devised to reduce the skill rerquired by the driver and to produce quick quiet gear changes.
They aim at synchronising the two halves of the gear engagement dog clutches, before the dog teeth made contact, by use of cone clutches.
LandRover LT77 & R380 Manual Transmissions
The LT77 & R380 transmissions were moste commonly fitted to Land Rovers.
The LT77 was generally fitted to vehicles from 1982 to 1994, and the R380 was fitted from 1995 to around 2007.
The LT77 is an updated version of an old Jaguar gearbox that found its way into current model British cars manufactured by British Leyland. The LT77 gearbox was so named because the distance between the main and lay shafts is 77 mm.
There were two version of this gearbox. The earlier version is known as the short stick version. The later version, introduced around 1988 is known as the long stick version.
The R380 box (So named because it is rated to 380 Nm of torque) was introduced as brand new LR gearbox across the entire Land Rover and Range Rover product lines. The R380 is a reworked LT77 with improved main shaft bearing arrangements that provided an overall strengthening of the box. The R380 still has the LT77’s 77 mm shaft spacing.
Since Rover was no longer part of British Leyland the LT prefix was abandoned.