Why is flat belt pulley domed??

D

derwen1959

Member

• Nov 9, 2022

• #1

I am looking at making very old sawbench with engine
into mobile unit just for casual use because I like sawing

New flat belt pulley will be required and I thought it would

be ok without dome but I have been told new pulley will
have to be domed . Why??

TIA

 

F

fastfarmall

Well-known Member

• Nov 9, 2022

• #1

So it stays on better!!

 

560Dennis

Well-known Member

Location

Madison,Ohio

• Nov 9, 2022

• #1

Tracks belt center

 

Janicholson

Well-known Member

• Nov 9, 2022

• #1

Flat belts run to the larger diameter of the pulley. Because that is centered, the belt finds its way there. because the most tensile strength in the belt is in the center of its cros section, the center of the belt climbs to the center of the convex pulley. Jim

 

rusty6

Well-known Member

Location

East central Sask.

• Nov 9, 2022

• #1

Yes,seems the high centre helps keep the belt on the pulley. I am finding a problem with mine on the ancient IH hammer mill. The wound paper pulley has decayed somewhat and is now more flat, possibly concave. I can't run the mill too hard or the belt will run off one side of the other. Never a problem on the tractor pulley but the mill needs the domed pulley.

 

R

rrlund

Well-known Member

• Nov 9, 2022

• #1

Even the big flywheel on a steam engine was domed.

 

P

paul

Well-known Member

• Nov 9, 2022

• #1

Self centering. Otherwise any tiny fraction you are off perfectly square shaft to shaft, the belt will fly off.

Paul

 

S

Steve@Advance

Well-known Member

• Nov 9, 2022

• #1

Is there enough material to grind it back to a convex?

Start it up and shape it with a flap disc in the 4 inch grinder?

 

I

IaLeo

Well-known Member

• Nov 9, 2022

• #1

One Iowa farmer cured the belt running off the big pulley sticking out of his corn crib that ran the inside ear corn elevator. He welded a 1" wide by 1/8 thick flat iron strap around the middle of the pulley! Leo

 

R

Russ from MN

Well-known Member

Location

Bemidji MN

• Nov 9, 2022

• #1

I see the recommended amount is 1/16 inch per foot of pulley width, I used to think it was more than that. I made a pulley for our JD M from scratch, out of a piece of 6 inch sch80 pipe. Probably not the correct diameter, but it was just for looks anyhow.

 

G

Greenfrog

Member

• Nov 9, 2022

• #1

Belt will ride to the center. Self centering.
My Dad had an old post drill press and rigged up an electric motor and a V belt ran on the flywheel. I always wondered what kept a v belt on that pulley. It was domed. High in the center. Ran that way for years. Its physics!

 

G

Greenfrog

Member

• Nov 9, 2022

• #1

Use belt dressing. Its sticky.

 

G

Greenfrog

Member

• Nov 9, 2022

• #1

Good idea

 

P

Patsdeere

Well-known Member

• Nov 9, 2022

• #1

Side conversation, does it matter if one or both belt pulleys are domed?

 

W

Wheat47

Well-known Member

• Nov 9, 2022

• #1

Seems like I read that the angle of the pully should
be 1 1/2 degree from the center.

 

T

T.R.K.

Well-known Member

• Nov 9, 2022

• #1

My opinion is it matters more if the pulleys are rather far apart. If the pulleys are side by side, you probably can get by with only one being crowned.

 

Q

quefan

Member

• Nov 9, 2022

• #1

If it is already poor, some duct tape
applied to create a crown may help you
out.

 

Goose

Well-known Member

• Nov 10, 2022

• #1

The belt always rides to the highest spot on the pulley.

With a slight dome in the pulley the belt will ride to the center.

 

G

gene bender

Well-known Member

• Nov 10, 2022

• #1

flat pulleys were always domed to keep the flat belt centered and stay on the pulley