Ha Ha Ha.... Oops!!
I said the numbers were reasonably easy to calculate; but I still got one
wrong. Something about those hollow spots all the gray hairs lead to.
Anyhow I figured that the energy in the 50 gallon tank at 5000 psi would
ideally lift 4000 lb truck only 19 feet. I was off by a factor of 60. (60
seconds in a minute) The calculation actually comes out to 1138 feet. That
suggests that hydraulic energy storage braking on a long hill might be very
possible and suggests that this scheme might indeed be practical for more
than just local delivery trucks.
What also struck me was that I do not see a real reason why a high pressure
pump/hydraulic motor unit cannot be built into the transmission of such a
truck and stored power transmitted to and from the rear axle via the
conventional driveshaft. This would essentially allow trucks as they are
designed today to adapt this hydraulic hybrid scheme without major design
changes. Perhaps even an aftermarket retrofit scheme is possible, though I
think with the cost of special high pressure tanks, high pressure hydraulic
pump, drive shaft connectors, mounting brackets, electric clutches, 60 odd
gallons of hydraulic oil and all the hydraulic lines and controls it
wouldn't have a very good payback even with $5/gallon fuel costs.
Sorry about the calculation mistake. Ed Weldon
----- Original Message -----
From: "Ed Weldon" <23.weldon@comcast.net>
To: <BWANA343@aol.com>; <jolylance@earthlink.net>;
<land-speed@autox.team.net>
Sent: Thursday, January 01, 2009 9:17 PM
Subject: Re: [Land-speed] Non-LSR Hydraulic Hybrids
> ....... And note that the size of accumulators needed
> to store the energy that you try to recover from a fully loaded truck
> descending from say a 1000 ft elevation would be enormous. The numbers
are
> reasonably easy to calculate.
> ........Good for a light delivery truck around town with short hills. Out
> on the freeway that energy would get a 4000 lb truck a bit less than 500
> feet up a 4% grade (19ft in elevation) before it would be used up not
> counting the losses from aerodynamics, tire friction and drive train
> friction. Still looks reasonably good for urban light delivery use.....
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