Re: Mechanical Tach. Drive

[n9ads@domain.elided (Howard R Pletcher)]

I don't know anything about mechanically driven tachs other than those
that were dirven off the distributor, but I do want to suggest that
unless this were a SMALL cement mixer on a Loadstar chassis, whatever
your find about how it was driven probable won't be applicable to your
V-304/345/392 as the engine was likely one of the large V-8 series
(V-401/461/549) and about the only thing common between the two series
was the fact that they had 8 cylinders and an IH logo.
 
If it was connected to the PTO, it's possible it could be on the input
side so that it could be looking at a higher RPM than the drum.  In
addition, it seems that usually a drum has a small gear driving a very
large one on the drum, so a lot of the reduction is there.  I'd think the
final drum RPM for transport is in the single digits, although they have
a higher speed for mixing and dumping.

Howard Pletcher
Howteron Products Scout Parts

On Mon, 17 Aug 1998 08:57:50 -0600 (MDT) PB Schechter <pb@domain.elided>
writes:
>>>I couldn't see very well into the engine
>>>compartment, but I followed the cable (with my hand) from >where it 
>went
>>>through the fire wall to where it ended:  it was screwed on >(just 
>the
>>>way it was screwed on to the back of the tach, and just the >way the
>>>mechanical speedo cable screws on to my 1966 Volvo) >"somewhere" (I
>>>couldn't see where, remember) at the back of the engine or >the 
>front of
>>>the tranny.
>
>>Being as this was a cement truck, could the tach be related to the 
>PTO?
>>Dennis who knows little to nothing about PTO's, but thinks it would 
>be
>neat to
>>have one.
>
>Someone else suggested this, and it seemed plausible to me, at first.
>However, then I started thinking about the cement drum spinning 1,000
>RPM, or 2,000 RPM (this is a 4K RPM tach), and it started seeming less
>plausible.  I think that the 4,000 RPM scale, and the 3,XXX RPM rev 
>limits
>on the IHC V-8s (I'm pretty sure the cement truck has an 8), is too 
>much
>of a coincidence to be a coincidence....
>
>PB Schechter
>'65 Travelall *without* a tach (so far)
>
>
>
>
>

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