spur gear vs rack and pinion design

can we use the same design calculations for designing a rack and pinion arrangement as we do with the two straight spur gears in mesh

Reply to
jas
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Yes.

In fact, standard gear hobbing uses a rack-shaped cutter to machine spur gears. It's the magic of the involute form that any diameter gear (including the infinite-diameter rack) will work.

Hth, Fred Klingener

Reply to
Fred Klingener

then how can we calculate number of teeth for rack

as for spur gear number of teeth = diameter/ module

but for rack we have no diameter

Reply to
jas

A rack is a gear with infinite (arbitrarily large) diameter.

Ned Simmons

Reply to
Ned Simmons

Talk about the tooth pitch instead.

Tooth pitch is the developed length between the teeth along the pitch circumference. On a spur (pinion) gear, it's a circular arc. On a rack, it's a straight line.

Spur gear pairs roll on tangent pitch circles. Pitch circle of the pinion rolls on the rack pitck line.

Hth, Fred Klingener

Reply to
Fred Klingener

if number of teeth on a spur is pitch diameter/module Then tooth spacing on the pitch circle is pitch circle circumference / number of teeth or pi X D / (D/module) = pi X module. This is evidently the tooth pitch you want on the rack.

Brian Whatcott Altus OK

Reply to
Brian Whatcott

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