Timing belt drives

"Clare Snyder" wrote in message news:***@4ax.com...

Any of you guys have experience with timing belt drives? I need as
compact as possible 1 1/2:1 reduction from a 600 rpm 2.5HP engine
(3600 crankshaft RPM with 6:1 reduction) then another 1 1/2:1 after
that (so lower speed higher torque) ( total reduction 13.5:1).This
will be driving a 20 inch diameter 2 inch wide tire/wheel.

How wide and how large do I need the small sprocket? For simplicity I
would likely like both stages identical. This simplifies everything
including tensioning
Small sprocket on output shaft driving large sprocket on jackshaft
turning small sprocket driving large sprocket spinning on output shaft
of the engine/gearbox with wheel attached to that sprocket. Distance
from center of small sprocket to outside of large sprocket cannot
excede 7 inches.

Is this possible/feasible???

--------------------------------
I've designed only vee belt drives. Drive belt manufacturers provide
detailed design information on line, which I studied after my guesses with
parts already on hand failed. I hadn't adequately accounted for the high
peak to average torque ratio of a one cylinder 4-stroke gas engine.

Vee belts have the advantage of being able to slip by engaging the idler
clutch pulley gradually, to accelerate from rest. On my bandsaw mill the ex-
motorcycle wheels need several seconds to get up to 60MPH. The $99 HF engine
may stall during engagement unless running about half speed.

On an old Maytag washer the vee belt slips for quite a while as the drum
spins up to speed in the rinse cycle. It's a special belt, a standard one
with exposed rubber grips too tightly. The motor slides against springs to
let the position of the separately driven water pump control the drum belt
tension. Pushing the motor inward to loosen the belts reduces its starting
current surge to let a 3KW generator run it.

James Waldby

2024-09-02 17:27:03 UTC

Post by Clare Snyder
Any of you guys have experience with timing belt drives? I need as
compact as possible 1 1/2:1 reduction from a 600 rpm 2.5HP engine
(3600 crankshaft RPM with 6:1 reduction) then another 1 1/2:1 after
that (so lower speed higher torque) ( total reduction 13.5:1).This
will be driving a 20 inch diameter 2 inch wide tire/wheel.
How wide and how large do I need the small sprocket? For simplicity I
would likely like both stages identical. This simplifies everything
including tensioning

I've seen some timing belt power transmission calculators online,
which account for RPM, small pulley diameter, required torque, etc,
but haven't done a design. The `AI Overview` from a google search for
`timing belt drive power sizing` has about 6 bullet points, each with
a link, that get to some design webpages or calculators.

I think an auto engine timing belt handles 15 to 25 HP, which you
could scale down from or get parts from. Depending on what your app
is maybe one stage of planetary gear reduction as in drill motors
would work; and there are some inexpensive electric bike clutches that
look like 4"-diameter planetary drives but might be irrelevant -
https://www.amazon.com/AMLESO-Electric-Planetary-Clutch-Motor/dp/B09XVL1NV7
- besides having nylon gears.

Post by Clare Snyder
Small sprocket on output shaft driving large sprocket on jackshaft
turning small sprocket driving large sprocket spinning on output shaft
of the engine/gearbox with wheel attached to that sprocket. Distance
from center of small sprocket to outside of large sprocket cannot
excede 7 inches.
Is this possible/feasible???

Bob La Londe

2024-09-02 17:45:01 UTC

I've seen some timing belt power transmission calculators online,
which account for RPM, small pulley diameter, required torque, etc,
but haven't done a design. The `AI Overview` from a google search for
`timing belt drive power sizing` has about 6 bullet points, each with
a link, that get to some design webpages or calculators.
I think an auto engine timing belt handles 15 to 25 HP, which you
could scale down from or get parts from. Depending on what your app
is maybe one stage of planetary gear reduction as in drill motors
would work; and there are some inexpensive electric bike clutches that
look like 4"-diameter planetary drives but might be irrelevant -
https://www.amazon.com/AMLESO-Electric-Planetary-Clutch-Motor/dp/B09XVL1NV7
- besides having nylon gears.

I didn't read all of that, but my problem with timing belts relates to
CNC motor drives. If I didn't get the tension perfect they would either
exhibit backlash or they would sap power from the system at a much
higher than expected rate.

That being said I have seen a cog belt with cog pulleys used on a fairly
powerful pulley with good effect. The 5hp motor on my Hurco mill uses a
1:1 cog belt to drive the spindle... and Hurco rated the mill at 4HP.
LOL.

I don't have the experience with them, but everything I've read
indicates a harmonic drive is the magic sauce for some applications.

--
Bob La Londe
CNC Molds N Stuff
--
This email has been checked for viruses by AVG antivirus software.
www.avg.com

Clare Snyder

2024-09-03 04:57:18 UTC

I've seen some timing belt power transmission calculators online,
which account for RPM, small pulley diameter, required torque, etc,
but haven't done a design. The `AI Overview` from a google search for
`timing belt drive power sizing` has about 6 bullet points, each with
a link, that get to some design webpages or calculators.
I think an auto engine timing belt handles 15 to 25 HP, which you
could scale down from or get parts from. Depending on what your app
is maybe one stage of planetary gear reduction as in drill motors
would work; and there are some inexpensive electric bike clutches that
look like 4"-diameter planetary drives but might be irrelevant -
https://www.amazon.com/AMLESO-Electric-Planetary-Clutch-Motor/dp/B09XVL1NV7
- besides having nylon gears.

I didn't read all of that, but my problem with timing belts relates to
CNC motor drives. If I didn't get the tension perfect they would either
exhibit backlash or they would sap power from the system at a much
higher than expected rate.
That being said I have seen a cog belt with cog pulleys used on a fairly
powerful pulley with good effect. The 5hp motor on my Hurco mill uses a
1:1 cog belt to drive the spindle... and Hurco rated the mill at 4HP.
LOL.
I don't have the experience with them, but everything I've read
indicates a harmonic drive is the magic sauce for some applications.
--
Bob La Londe
CNC Molds N Stuff

I've decided to just try a bigger engine - - -

Engine has 6:1 reduction - direct driving a 20 inch wheel to move 300
to 350 lb. New enginr is 2 9/16 bore and 2 7/16 stroke

Bob La Londe

2024-09-03 17:33:37 UTC

Post by Clare Snyder

I've seen some timing belt power transmission calculators online,
which account for RPM, small pulley diameter, required torque, etc,
but haven't done a design. The `AI Overview` from a google search for
`timing belt drive power sizing` has about 6 bullet points, each with
a link, that get to some design webpages or calculators.
I think an auto engine timing belt handles 15 to 25 HP, which you
could scale down from or get parts from. Depending on what your app
is maybe one stage of planetary gear reduction as in drill motors
would work; and there are some inexpensive electric bike clutches that
look like 4"-diameter planetary drives but might be irrelevant -
https://www.amazon.com/AMLESO-Electric-Planetary-Clutch-Motor/dp/B09XVL1NV7
- besides having nylon gears.

I didn't read all of that, but my problem with timing belts relates to
CNC motor drives. If I didn't get the tension perfect they would either
exhibit backlash or they would sap power from the system at a much
higher than expected rate.
That being said I have seen a cog belt with cog pulleys used on a fairly
powerful pulley with good effect. The 5hp motor on my Hurco mill uses a
1:1 cog belt to drive the spindle... and Hurco rated the mill at 4HP.
LOL.
I don't have the experience with them, but everything I've read
indicates a harmonic drive is the magic sauce for some applications.
--
Bob La Londe
CNC Molds N Stuff

I've decided to just try a bigger engine - - -
Engine has 6:1 reduction - direct driving a 20 inch wheel to move 300
to 350 lb. New enginr is 2 9/16 bore and 2 7/16 stroke

In the words on Tim Allen, "More power!"

--
Bob La Londe
CNC Molds N Stuff
--
This email has been checked for viruses by AVG antivirus software.
www.avg.com

Clare Snyder

2024-09-05 12:43:46 UTC

Post by Clare Snyder