From: Bruce Kalin (convoy@mtaofnj.us)
Date: Thu Nov 25 2004 - 08:51:45 PST
Noel,
I agree with much of what you have said but, I have to take a small
exception to your writing. It is my personal experience that the size of
the "box" is not the determining factor in the speed of the shift,
unless you were referring to the weight.
However, a change in the load size will definitely change the speed of
the shift required in the same vehicle. This could be an empty truck vs
a full 53' container or, an empty bus vs one with 53 passengers and,
full luggage compartments. Loaded vehicles, for the most part, require a
faster shift than an unloaded (unladen) vehicle.
In the 70's, when I drove both trucks and busses, as well as being a
driving instructor and safety manager, there was an incredible
difference in the shifting of these vehicles. Mack trucks were known to
be very slow shifters, while vehicles with a Cummins engine needed to be
shifted more quickly. GMC powered vehicles required the fastest of
shifts in both trucks and buses. The transmissions were rarely a
determining factor in the shift speed with the same engine. Even the
addition of turbos changed the shift speed very little.
Buses manufactured by Eagle had Cummins engines and, were much slower to
shift than any bus made by General Motors. In fact, city transit buses
were much smaller and lighter than road coaches, yet those with a manual
gear box required much faster shifting than a road coach. The eight
cylinder buses always required faster shifting than the 6 cylinder
vehicles.
When I was safety manager for a bus company in NYC, it was always good
for a laugh when we would get an over the road truck driver wanting to
be home each night, apply for a job as a city route bus driver. Those
who would overly brag of their truck driving abilities, would never be
told before their road test, how incredibly fast they needed to shift
the bus. Inevitably, they would miss shift, after shift, after shift. If
they continued to grind gears, or try to force the shift, they were
usually taken out of the seat at that time. This was not the type of
driver we were looking for to haul live people. If they were willing to
show that maybe their might be more to learn than what they already
knew, after we had a good laugh at their expense, we would show them the
proper way to shift. It didn't take them long to catch on after that,
and they were usually hired and made good drivers.
In fact, it is easier to maneuver a cab over tractor with a 40' box down
city streets than it is to turn a 40' bus with three axles. Two axle
buses, again turn differently than three axle buses. And, for required
MV content, we have been shown that MVs with single rear wheels turn in
a shorter diameter than those with dual wheels. Single rear axles turn
again, in a different pattern.
Just my experience - yours may differ.
-- Bruce Kalin Convoy coordinator Coordinator@eastcoastconvoy.com http://www.EastCoastConvoy.com USMC MTA, MVPA, MTA NJ, NCMVPA
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