Thread: Too much time on my hands

What you are talking about is identical to an overdrive (available for this transfer case I think) but with a reduction gear not a step up. Do a search on overdrives will give you a good idea as to what has been tried.

The detail design is likely to be more important than the what type of gearing or method of actuation you use. Lubrication is likely to be a critical consideration.

John

GKN (?) electronically operated overdrive. Moonshot gearing for LR's. Was in that famous tech bible 4WD Monthly a couple of years ago.

cheers, DL

Ashcroft make one already..... The underdrive.

http://www.ashcrofttransmissions.co.uk/category_12.html

Bill Larman has done it using an old Jeep Quadra Trac t/case onto the back of an LT230.
The original Quadra Trac T/case used a planetary gear low range, and Bill did a cut and shut using this bolted onto the back of the Land Rover t/case.
Very clever.

Ashcrofts build their famous Underdrive.
Ashcroft Transmissions



By installing the Underdrive we have created a four range transfer case, in addition to the stock high /low we have an intermediate range and a super low range. Typically the ratios could be 1.2/1.4/1.6 high, high x 2.69 intermediate, 3.32 stock low, 8.93 super low. The intermediate range is a useful gear split between stock high and stock low High and Low ratio will remain unchanged but when selected the underdrive will give an additional 2.69 reduction, this makes a low, low ratio of 8.93 (3.321 x 2.69). This gives the best of both worlds, high stays the same for road use, you have stock low for running about between sections and you have underdrive low for crawling over obstacles or winching.

its been done but not as compactly as your trying to.

from memory yes you can remove the input gear of the lt230 through the pto cover plate/rear support bearing plate.

Id be going with a square cut planetry setup in a fairy type overdrive box with the gearbox input driving the sun and the planetry carrier as the output. Id have the annulus made up as part of a sliding syncro clutch mechanism so that when you want 1:1 it slides forwards under control of the selector and the syncro engages directly onto the back of the sun gear and when you want under drive it slides backwards and the syncro housing on the outside of the annulus grabs at its corresponding part on the back of the housing.

I'll stand corrected.... that ashcroft one looks exactly as Id imagined it but neater