MUCH MORE ON BRAKES

July 22, 2011 Vol. 7, No. 15

Please, bear with me at the start of things here. I’m going to clear up a matter of language and meaning before I write anything else. Won’t take long.

Engines. Motors. Are they one and the same?

I ask because every once in a while I get a snippy e-mail from folks telling me to quit using the words interchangeably. Nope, I won’t.

An engine is a motor and a motor is an engine, period.

The usual complaint I receive claims that a motor can only be electrical, like the thing that drives your workbench grinder or hundreds of other such things in your life and mine. True, in common usage we never refer to those smoothly spinning marvels as ‘electric engines’ but we could. That’s what they are. We could also call them ‘electric machines’ but we never do.

I went to Merriam-Webster online — my 2-volume Oxford is on the top shelf and  I’d have to get up — just to clarify things. Here’s how it defines ‘motor’… a. a small compact engine; b. internal combustion engine; c. a rotating machine that transforms electrical energy into mechanical energy.

Synonyms for ‘motor’? Engine and machine.

So there.

Now on to serious stuff, including a return visit to CFMVSS 121.

BETTER STOPPING, THE BENDIX VIEW. Last time out I reported on a webinar conducted by the big guys of Meritor’s brake operation, Chad Mitts and Joe Kay, about the new CFMVSS 121 stopping-distance requirements. They focused on the differences between air disc brakes and good old S-cams and how they can both meet the new standard.

I figured the competition’s approach would be well worth investigating too, in fairness, so I arranged a phone chat with Gary Ganaway, director and marketing chief at Bendix Spicer Foundation Brake. We talked for quite a while.

Phase 1 of the rule, to remind you, demands that a 3-axle tractor grossing under 59,600 lb be able to stop in 250 ft from 60 mph instead of the present 335. It applies to trucks built on or after August 1 in just over a week from now. Phase 2 kicks in on August 1, 2013 when all other configurations and weights are targeted. The 250-ft standard applies to most others, but bigger trucks — 3-axles above 70,000 lb and 4-axles above 85,000 lb — will have a 310-ft stopping-distance max.

The folks at Bendix are ready for all this, of course, with both drum and disc products. Earlier this year they introduced a new version of their Extended Service drum brake specifically to meet the new NHTSA standard. The improved single-anchor-pin ES brakes achieve higher performance levels through mechanical enhancements like more durable bronze bushings (instead of plastic) and precision cams, both of which contribute to better dimensional control and durability. But, as with Meritor, the biggest gain is through new "state of the art" lining materials.

Today’s S-cam brake is very, very different from the ones we’ve had in the past, a remarkably superior stopper, says Ganaway.

"This new friction is just outstanding," he told me. "In some configurations we’re seeing over a million miles on drum-brake linings. In highway use lining life has been simply incredible."

Bendix data suggests that a million miles is actually the mean, he adds, given this new friction on the current high-performance brake with its improved mechanical bits.

Ganaway notes that the big 16.5 brake may in some cases demand a bigger auto slack adjuster and a chamber-size increase from 20 to 24 sq in. The torque gain in going from an old-style 15 x 4 ES brake to the newest 16.5-in. type is substantial — from about 6500 lb ft to 9000, he says.