From: m35products (m35prod@optonline.net)
Date: Sun Jun 20 2004 - 08:24:12 PDT
Dr. David D. Doyle, of the Virtually-Virus-free Virtual Clinic wrote:
...HOWEVER, I have steered dead five tons with hydraulic power steering
(both original style and 800-style) and it is not fun without the engine
turning over (think clutched...or drive shaft out)......if you think a deuce
steers hard stock, try an M328 with its huge tires.
I suspect that is the reason the M35A3 has air assist steering...because
with air, there is a reserve (this can been done in hydraulics as well with
an accumulator, but I am not aware of anyone supplying such a system.) other
than the driver's brute strength. Perhaps it was felt this was an
improvement over the hydraulic power assist used on the larger trucks...
-----------------------
David, and All:
Happy Fathers Day, and "A little history of the Air-O-Matic products:"
In 1947, (approx) the AOM power steer company was formed with its new
product, the air-assisted power steering add-on kit. Not being a trucking
historian, I cannot attest to what the hydraulic steering situation was at
the time, but the AOM seemed to be a welcomed improvement over armstrong
steering then in vogue. The old sales literature points out the obvious
benefits of PS, and does not mention hydraulic as an alternative. Perhaps
someone more conversant with trucking history can illucidate us on its
(hydraulic steering) history?
AOM sells (or used to sell) conversion kits for practically any large truck,
assuming, of course, that the truck in question had an air supply. I have an
application guide here that lists the major truck brands and models, and the
applicable AOM conversion kits available. In addition, there has always been
available a so-called universal kit, which contains the basic parts, and a
generic mounting bracket, but final assembly is left to the intuitive
mechanic for completion.
The product has been in continuous use since 1947 to the present. It was the
OEM choice on Mack, and other big rigs; Bluebird, and other bus (coach)
models; and on American LaFrance fire apparatus. Unfortunately the new
owners of the AOM line have seen fit to dispose of all the inventory of
brackets for the various applications. This act of corporate vandalism
threatens to deprive us of the opportunity to continue the use of this
simple yet effective product. I heard about the disposal (of several
container-loads of steel) just a few weeks too late, or I would have
purchased the entire inventory. The good news is that the bean counters
were not allowed to get their paws on the original blueprints, so an
occasional customer with the odd 1953 Greyhound coach can still get a kit,
assuming I can get MY paws on the drawings, and an iron shop can build a new
bracket.
It may be interesting to note that up until just a few years ago, Roadway,
one of the country's largest delivery services, would, each year, buy a few
hundred over-the-road tractors, with sleeper cabs, highway gearing, and NO
power steering, and dispatch these rigs over the interstates. (Why no PS?
It was figured that they would be basically going straight ahead, with
little need for tight turns, and hydraulic systems place a parasitic load on
the drivetrain, reducing fuel economy.) When the tractors had accrued
1,000,000 miles or so, they would be re-shopped, and the sleepers would be
removed, the wheelbases shortened, larger radiators installed, and
Air-O-Matic power steering installed, and they would be sent out as
intra-city delivery tractors, in which environment power steering would be
beneficial. The tractors would then be run another million or so miles, and
the AOM PS units would perform perfectly.
Your astute observation regarding the reserve air capability is one of the
benefits that sells the system. AOM P/S has been the only mil-spec kit for
the 2.5-ton Reo since the 1950's. It was specified as an enhancement for
rear echelon and National Guard trucks, at first. Its ease of installation
and simple reliability were the selling points back then. Aggressive
marketing (and I suspect, golf and cocktails) resulted in the choice, by AM
General and TACOM, to select the AOM as the P/S of choice for the Extended
Service Program of the 1980's when the M35A3 series was being out-shopped.
Apparently the choice was either to reinvent the entire steering system
based on hydraulic components, or simply to apply the AOM to the stock
steering systems on the trucks. The choice was made, and it was a good and
economically prudent one. Air, it may be added, is free, at least under the
Republicans, but hydraulic oil is not.
Recent laughable assertions in a magazine, which shall, from now on, go
nameless in my writings, claim that one can deplete the air supply quickly,
rendering the AOM P/S less than the best choice. Since, in the event that
air IS depleted, the truck reverts to manual steering, and since a
hydraulically-operated system reverts to, well... no steering at all...the
benefits of AOM can easily be seen.
An M35 with a dead engine can be steered easily, as long as there is air
available. An M35 with a dead air system can still be steered (not easily)
because the AOM is an ASSIST, not a full-time system.
Arthur PS Bloom, Pres.
www.products.com
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