Thread: What is the benefit of a transmission handbrake?

With an intact drive line, the hand-brake works on all four wheels.

There is a Top-Gear episode where Jeremy Clarkson is testing a BMW X3 and attempts to drive it up a wet grassy slope, and of course loses traction. He then puts the Beemer hand-brake on and the vehicle slides back down the hill with the rear wheels locked and the front wheels rolling. This while a Range Rover drives seeming effortly up the same hill in the background.

It is more difficult to get a handbrake to work efficiently on disk brakes than with drums, so a transmission handbrake allows for the benefits of four wheel disks and the benefits of a drum handbrake.

Why don't you like the transmission handbrake?

A wheel hand-brake would have been handy on Taverners Hill (Sydney) when I broke a rear axle and had the F/W hubs disengaged. Wouldn't have been so bad except it was morning peak-hour.

Less equipment and thus weight.
Also all those moving parts are not in the water and mud.

you get the gearing advantage of the Diff and as previously mentioned depending on CDL and gear selection it works on all wheels.

It provides a second braking system thats completely independant of the normal braking system so that a leaking seal down at the wheels means you still maintain an effective brake.

Originally Posted by Lotz-A-Landies

A wheel hand-brake would have been handy on Taverners Hill (Sydney) when I broke a rear axle and had the F/W hubs disengaged. Wouldn't have been so bad except it was morning peak-hour.

What did you use for a stopper? Millers Brewery or the car auctions across the road?

Seriously, the trans. hand brake on my 1928 Dodge Standard Six is a ripper. There are three adjustments and if all are done in the proper sequence you have a hand brake par excellence. Just as well, as the self-energising service brakes, Midland mechanical "Steeldraulic" are all but useless in reverse and I have a steep driveway.

The major advantage of a transmission handbrake is that it enables a simple short linkage that is not exposed to offroad damage as is the case with a handbrake operating on the rear wheels.

However, the reason that all Landrovers directly descended from the original one have a transmission handbrake, is that this is what the original Jeep had, and hence what the first Landrover had. At the time the original Jeep was designed (1940), a transmission handbrake was a pretty much standard design feature, possibly because brake designers had not yet come up with a good way of having mechanical operation as well as hydraulic operation on the same drums. Those cars without a transmission handbrake either retained mechanical brakes (where the dual mechanism was external to the brake drums), hydraulic front and mechanical rear, or occasionally either separate drums or an external band brake on the same drums for the handbrake.

While Rover could have fitted a "conventional" handbrake in 1948, as the mechanism was available by then, the bowden cables used to operate them were notoriously unreliable in any sort of adverse conditions, as well as very susceptible to catching on things, and if indeed they were considered, it is just as well they were not used! And since the transmission brake is, as noted above, effective and reliable, there has been little reason to change until the most recent designs, which are not descended from the original Landrover.

About the only drawback is, as Diana points out, the loss of a parking brake if you break an axle and have the front hubs disengaged. But the footbrake still works. And there are worse failures possible on some other vehicles - one of my sons had the axle nut come off at speed on a Beetle, allowing the entire wheel plus brakedrum to come off, losing all brakes.

I have to wonder why you would prefer a brake operating on the rear wheels? While it is possible to have an effective mechanical brake on discs, the much higher force needed to apply the brakes means you need a very large mechanical advantage, which makes frequent adjustment necessary (probably via a potentially troublesome automatic adjustment), especially if the discs used are the service brake ones, and subject to wear. And the mechanical mechanism on the wheel brakes gets immersed even in shallow wading, and probably sprayed with water and road dirt every time it rains, where the mechanism for the transmission brake is mostly out of the weather.

John

This begs the question of why handbrakes went on the rear wheels. Mt subaru had the handbrake operating the main disk brakes on the front wheels. A very simple setup and the handbrake being on the front worked a lot better than those on the rear.

Seemed to work as good as a transmission brake when parked downhill.

Garry