I have a co-worker who does something to really tick off those who give others "the finger", or when a driver does something really dumb (like cut him off).
He makes eye-contact and makes sure they see that he gives them a "tumbs down" all while shaking his head side to side and mouthing the word "no". I've been in a car with him when he did this to a lady driving a Mercedes, and she just crouched in her seat and made like "a hole in the asphalt" after that.
I'm sure that others might not respond very well to a dissapproving vote on their driving, but it's better than swerving to run them off the road...
My two cents on the braking topic is similar to that of my performance driving knowledge - forced-air cooling the brakes (as I believe Chaz had suggested) is a good idea, so long as the incoming air doesn't have a lot of debris/contaminents. Engine braking is easiest for speed control (i.e. get in the right gear for the hill and your rig's weight and let the centrifugal/pumping losses of the engine drag down the speed of the rig). When "stock" engine braking is not enough, a supplemental engine braking system like a Jake will increase the pumping losses enough to not need to touch the service brakes (YMMV) - heat here isn't an issue (and I think that most will agree that on a 2-stroke, the engine will cool down quite a bit while the Jakes are running due to the lack of combustion on the cylinders).
Where Jakes aren't allowed or don't fit (due to regional restrictions [I'm in Ohio now and I see a lot of "No Engine Brake" signs around] or engine height clearance issues, since Jakes need taller valve covers) and there's extra drive-train length space available, a transmission retarder might be the right ticket (or you might have one on your tranny already) - caution should be used to ensure that the tranny fluid doesn't boil (transmission retarders work by restricting the flow of fluid which puts the fluid under imense pressure - creating a lot of heat), the heat in the tranny fluid needs to be rejected to the atmosphere to avoid build-up, so on heavy rigs or those with small fluid-to-air exchangers (and I think there are even some which exchange heat with the engine) - this may only be good for a short while, so "careful" use should still be the name of the game. A temperature gauge on the tranny fluid inlet should help manage the heat within the tranny.
For those who are using transmissions where retarders are not feasable, Jakes are hard to find, or concern for shaft breakage is a design consideration - a Telma is probably the ticket. A "Focal" model retarder can be mounted right to the differential's pinion input, and only requires electrical power to run. Again, caution should be used
in the design of a Telma installation (this is why Telmas are supposed to be installed by authorized installers/dealers) because the electrical system must be able to sustain the draw of a full-load Telma (up to 400Amps in some installations), and the heat which is rejected by the Telma must go somewhere "
safely" (i.e. it must be kept clear of wires, air lines, fuel lines, etc.).
After that, one can consider retro-rockets and parachutes to slow you down - but if you need to resort to this extreme, just give me a call before you hit the road so I can get off it
.
As an asside, with automatic transmissions and engine/jake braking one must ensure that the tranny's torque converter is in "lockup" or the engine resistance will be lost without the direct mechanical connection to the engine (a torque converter uses fluid resistance to rotate the transmission relative to the engine when the engine "turbine" is rotating faster than the transmission "turbine", when the inverse is the case, the converter resistance is lower so the trany turbine can spin much faster than the engine turbine - letting the rig go down hill faster without much of the rotational energy getting to the engine. A lockup clutch connects the engine turbine to the tranny turbine and the rotational energy can go both ways (engine to transmission or transmission to engine). I believe there was an article by Brian Diehl on how to force this for an Allison HT754 transmission on this board, and he may still have the web page on this topic up on his website. On my first trip, I found that downshifting out of "drive" into one of the numbered gears, kept the tranny in lockup all the way down to 15MPH (YMMV). If you can hear your prime mover while driving, a transmission in lockup should maintain roughly the RPMs when you reduce your pressure on the accelerator - while a transmission out of lockup should have the engine RPMs drop off sharply with less throttle (causing a
coast).
I won't comment on the braking method that anyone
should use, I personally use the pumping but this is due to my track time in cars (where a constant pressure may end up with locked up wheels, whereas a "pulse" or "cadence" braking would allow wheels which had locked up a chance to re-gain traction and help keep the vehicle track correct). With ABS, this isn't much of a concern - but since most of our old rigs don't have ABS, it's a point to bring up (if you're used to cadence braking you're more likely to use it correctly in an emergency).
Cheers!
-Tim
P.S. My ideal system would include both a Telma and Jakes, with the option to pick which or both should be used in a specific region (4-position switch Off-Jake-Telma-Both for selection), with both a separate pedal for retarder control and an air/retarder brake pedal to control the level of retarding power (with modern PWM tecniques, we can get more than a 2-to-4-step level control on electrically controlled retarders, now we can get more than 32 steps for better control). -T
