That yellow knob!

Ever wondered how the land rover series selectable 4 wheel drive works? I thought I had a good idea until I stripped one down and started to rebuild it.

The low/high ratio part is nice and easy, the lever slides a pair of gears on a splined shaft to mesh with gears on a the intermediate shaft in the transfer box.

But what about 2wd/4wd?

This is more tricky to describe - I'll try to post some pics or diagrams soon, a picture painting a thousand words and all that.

Low 4wd,

The hi/lo lever (the one with the red button:->)when moved back for low also pivots a small link the other end of which moved forward sliding a shaft on which is the dog clutch, engaging the front output shaft.

Hi 4wd

This is the clever part, the pivot point for the link which operates the dog clutch shaft is actually the pin operated by the yellow button. Pushing the yellow button withdraws the pin from the center of the link, making it no longer pivot, now when the red lever is forward, the spring on the dog clutch shaft forces it to engage the dog clutch.

This is why to get out of 4wd Hi, you have to move the red lever, this moves the link until the point where the spring on the yellow button rod pushes the pivot pin back in.

Confused. Hopefully some diagrams soon.