From: Larry Tighe (larryradio@worldnet.att.net)
Date: Sat Feb 14 2004 - 14:24:34 PST
It's interesting to follow the "thread" of improvements in Mil Veh's as the
army took the same slow steps in aviation too.
The original helicopter, Bell's OH-13 series, civilian Bell 47, lost it's
hydraulics when the engine quit. As the engine drove the hydraulics which
operated the collective and cyclic. It was a real bear to do an
autorotation with hydraulics "off". After the Bell, the hydraulic pump was
connected to the aux. gear box on the main transmission and so, no loss of
"steering" hydraulics as long as the rotor was turning.
As the Huey progressed to the "M" model, like the truck with an air assist,
the M model had an "accumulator" that gave you 4 full movements of the
collective and then it locked hard in place. The same thinking, I guess,
was the air tank giving the truck the steering assist....again, an "after
market" improvement.
Too, the Huey, should it crash in forward motion, the rotor mast and
transmission would tip forward and the stabilizer bars on the rotor would
get the pilots in the back of the head as they crashed through the roof of
the cockpit. That roof could have been improved but......
Until lately, I think the army always considered people expendable when they
could have saved them with a little extra money spent. Now, rotary is
mostly twin engine and all the safety that implies. Nice to see the ground
vehicles are getting safer.
Lar
M151A2
HMMWV
----- Original Message -----
From: "m35products" <m35prod@optonline.net>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Saturday, February 14, 2004 2:02 PM
Subject: Re: [MV] I-70 Federal study
> Very well put, David.
>
> I might immodestly point out that one of the many benefits of the
> Air-O-Matic steering modification is that in the event of engine failure,
> the power steering continues to provide safe, continuous operation, for as
> long as air remains in the system. Additionally, even after exhausting all
> available air, the steering simply reverts to Armstrong steering. This
> allows a driver to manuever the truck into a safe zone, without steering
> wheel lock up. Instead of fretting about steering lockup, our government
> should have taken a look at their own steering modification
recommendations,
> from a previous generation of trucks.
>
> A P Bloom
>
>
> ----- Original Message -----
> From: <DDoyle9570@aol.com>
> To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
> Sent: Saturday, February 14, 2004 1:15 PM
> Subject: Re: [MV] I-70 Federal study
>
>
> > I am not familiar with the report Ron referred to regarding the safety
of
> the G-742 (M35-type)trucks, however I am familiar with one critical of the
> M939. That report can be found at:
> >
> > http://www.gao.gov/archive/1999/ns99082.pdf
> >
> > It states that the M939 is 21 times more likely to be involved in a
fatal
> accident than a M35A2. This reports states that in December 1995, the 939
> family was limited to 40 MPH on road, or 35 MPH off-road, pending
resolution
> of hte safety issues.
> >
> > The trucks, when ordered, were intended to operate off-road 80 % of the
> time, and the NDT was a good tire for this, given the initial premise of
one
> tire for use in snow, mud, dirt, sand....rather than matching the tire to
a
> known terrain as off-roaders do. However, in practive the trucks on and
> off-road uses were reversed, and the NDT is NOT a good on-road tire during
> rain. This is not a new revelation, I have a WWII training film on this
> subject. Nevertheless, given the increased on-road use of the trucks, it
> was decided to try new tires. The result of this was the super-single
> radials.
> >
> > It was found that a lightly loaded truck, under heavy brake application,
> had a tendency for wheel lock up, and ENGINE STALL, with inherent loss of
> power steering, loss of control and roll over. The suggested remedy was a
> change to the brake proportioning, AS WELL AS the installation of anti
lock
> braking systems. These changes, including tires, were expected to cost
> $3800 per truck.
> >
> > At the same time, it was decided to modify the accelerator linkage on
> M939A2 trucks, and add Roll over Protection as the cabs were replaced
during
> normal maintenance. This was expected to cost about $3600 per truck.
> >
> > Something that is overlooked in almost every posting about towing trucks
> is that NONE of us follow the military procedure. By reading the TM that
> accompanies the military towbar, we find that if we are flat towing
another
> vehicle with the tow bar, there is to be a driver in BOTH vehicles. This
> solves the steering, lighting, and brake lighting problem. None of us do
> this, and in most areas it would be illegal for us to do this. And the
> military, at least in this area, seems to RARELY flat tow anything, rather
> we always see a wrecker (5 ton or HEMMT) towing with one end of the towed
> vehicle supported by the wrecker shipper.
> >
> > With respect to the legality of amber beacons in some states. My
position
> is, the police may stop me, the judge can fine me, but that trucker in
> Illinois executed these two fellows. I'll take my chances with the fine.
> >
> > My .02,
> > David Doyle
> >
> >
> >
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>
>
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