In a message dated 6/18/00 4:06:48 PM Central Daylight Time, spike66@ibm.net
writes:
> Hmmm now Im more curious than ever. Composites wouldnt be any
> good for that purpose and I dont know of any materials breakthrus
> in the past several years in metals, unless they are using one of those
> new tricky sintering technologies. But I wouldnt think that would be
> any good for a part as big as a rocker arm or a pushrod. Curious.
I wasn't necessarily think new materials, per se. for instance, we're seeing
a lot more titanium stuff in things like racing engines, because the tech
for working with it has gotten better. But I was just guessing there.
> > The benefits of getting rid of a long timing belt or chain, with all
the
> lash
> > problems and tension-maintenance issues they give rise to, may offset the
> > reciprocating mass cost of the pushrods.
>
> Ja, but I would think the answer to timing chain lash is a direct shaft
> drive with bevel gears for the overhead cam shafts. That system is
> still reasonably light, reliable and very durable under high revs.
Well, I'll reveal my ignorance: I've never heard of a shaft-driven ohc
system. Are there such in production???? I thought they were all belt- or
chain-driven.
> I notice the motorcycle world going back to push rods, which shocks
> me, but I assumed the reason was to imitate Harley Davidson. Have
> you seen the Japanese Harley clones? Yamaha is building one that is
> so Harley-like you need to be right next to it to tell the difference:
> pushrod, fat bob tank, softtail-like back-end, air cooled 98 CI Vtwin,
> even a belt final drive. They must stopped. I want one. {8^D spike
Uh oh. We've now identified an unbridgeable gap between us, Spike old man.
Back in my biker days, I decided there were three kinds of bikes and three
kinds of bikers: "Profilers" (Harley-style, low-cut seats, long rake-angles),
"Cafes" (tucked-in, racer-style) and "In-betweens" (classic "straight" sport
bikes and touring bikes). Although for practical reasons my wheels were
always of the latter category (since during most of that time a bike was my
only wheels), my heart was in the middle category. Had I not gotten out of
bikes, I'd be driving a "katana"-style bike today. I always considered
Profilers to be ill-considered pieces of "street jewelry", designed to look
good from the side but having evil handling manners, mainly due to the
rider's constricted position and the overly-long wheelbase.
Greg Burch <GBurch1@aol.com>----<gburch@lockeliddell.com>
Attorney ::: Vice President, Extropy Institute ::: Wilderness Guide
http://users.aol.com/gburch1 -or- http://members.aol.com/gburch1
ICQ # 61112550
"We never stop investigating. We are never satisfied that we know
enough to get by. Every question we answer leads on to another
question. This has become the greatest survival trick of our species."
-- Desmond Morris
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