I was curious as to why certain belt driven Whirlpool/Kenmore washers have a fast agitation speed of only 46 strokes per minute(then how slow is the gentle speed).

The fast agitation speed of a Whirlpool/Kenmore BD washer is actually 68 strokes/minute. Not sure what the gentle speed is...perhaps someone else might know?

I Memory serves correctly, that your both correct, but just in the wrong order. The "B-D" Regular/Fast Agitation is the 68-SPM and the Delicate/Slow Agitation is 46-SPM.

Peace and Happy "Belt-Drive" WP/Kenmore Washing, Steve
SactoTeddyBear...

The speeds called out by Whirlpool based on lots of reading are as follows: High Speed 68 s.p.m. with 195 degree stroke arc. Slow speed 46 s.p.m. I have never seen anything in my reading about the later 3 speed machines such as my 1972 Lady Kenmore, but if I did my math right, and I might not have, I would put the handwash speed at no more then about 27 s.p.m.

I remember reading that certain 1956 and 1957, Kenmore and Whirlpool models used a "slo-stroke" transmission. In these models, the agitate speed on High speed was only 65 s.p.m. and Slow speed was only 42 s.p.m. The stroke arc was also different at 220 degrees.

According to this Whirlpool manual that I am relaying this information from 1962, there were numerous problems with this transmission as pointed out by TSB#L107. I have never been able to locate this bulletin on paper, but my Uncle who repaired many early Whirlpool and Kenmore washers said it was due to poor lubrication galleries and also the notorious worn agitate gear.

Hope this provides some little known insight.
Walt