X-Mozilla-Keys:
Jeff Spitzer wrote:
DAVEIPETZ@aol.com wrote:
FYI
Morse catalog PT-93 shows chain calculations for HV 1/2 inch pitch 1 inch
chain
on a 27 tooth drive sprocket turning 5400 RPM at 177 hp. for internal
combustion engines with damping a service factor of 1.3 should be used.
177 X 1.5 width =265 hp X .77 service factor =204 hp.
Paul wrote:>
I suspect those ratings are for automotive use.
I do know the chain in a Cadilac front drive car is about 1.5 inches
wide but the average HP of that car is about 30 to 40 HP.
Peak HP is close to 300 HP.
According to most engineering handbooks the ratings are much more
modest.
Marks' Standard MEHB Tenth Edition 1996 page 8-63
1/2 pitch 29 tooth sprocket 4000 RPM 25 HP
3/8 pitch 29 tooth sprocket 6000 RPM 18 HP.
Per inch of width. Ideal drive conditions 20,000 hour life.
ANSI B29.2-1957 (R1971)
Perhaps it is a difference in life but whatever it is, it is
very surprising indeed.
Paul Lamar
Paul and Bill,
I am using the same catalog as cited above. I keep forgetting to actually
open it when I'm home but the numbers above sound very much like my own. I
do not have first hand knowledge of the ratings but worked with a respected
engineer who had certified a HV box in NZ. I noticed that Bill had
referred to the chain as "Silent" I don't know why these chains look alike
but don't perform alike but the section in the Morse catalog that follows
HV gives much lower ratings for "silent chain" that looks almost identical
to HV to me. Anyway, my friend quoted the Morse engineers as saying
something like 100 hp/inch width = forever if properly done. He never
experienced a chain failure or excessive wear on his unit. I'm a little
disappointed with Paul's singlehanded bashing of the catalog ratings as
"automotive". There is clear guidelines in the catalog for duty cycle and
the drives are geared toward industrial use which typically is much more
demanding than automotive. Regardless, the ratings are completely defined
and contain no such "hidden" de-rating. I would usually be relatively
comfortable just to follow the catalog ratings knowing that they are
usually conservative (from a company like Morse). In this case I have
independent verification that the ratings are valid in my application. I'm
not worried. I could be wrong :-)
Jeff Spitzer
"Automotive" ratings is the only plausible reason there is such a
difference
in ratings. I.E. 30 HP verses 100 HP per inch.
Maybe the silent chains are made from chewing gum and the Morse chains
are
made from unobtainium :-). Kryptonite?
Please ask Morse to explain the difference?
You do admit the Cadilac is 30 to 40 HP average do you not? :-)
Paul Lamar
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