Belt and Pulley 1

[Omar7amdi]

Hello,

Suppose this pulley is latched to a motor's shaft residing on the floor. On the ceiling there is a similar pulley hanged on a hook. At the center of the belt's height there is an object carried by the belt. When I ran the motor sometimes the belt's teeth does not lay on the pulley's groove which causes the object's position to not be coherent with the motor's rotation. I tightened the belt and the problem still comes from time to time? The motor is moving forward and backward.

is there any idea how to solve this problem?

Thanks

 

[Jboggs]

What is your question?

 

[Omar7amdi]

The belt between the two pulleys is not perpendicular. We used two rollers at the bottom end of the post to line up the belt before entering the pulley's groove. Since the belt is not perpendicular, would this situation cause a problem after a while of service?.
By the way, I'm an electronic engineer working with a mechanical engineer.
Thanks

 

[MikeHalloran]

Does anyone there have a phone with a decent camera in it?

Mike Halloran
Pembroke Pines, FL, USA

 

[Omar7amdi]

Hi All,

We tightened the belt but from time to time the belt slips and causes a displacement to the trolley.
The pulley is on the motor shaft . On the other end of the belt is a roller. The two rollers near the
pulley to guide the belt and forbid the belt vibration. Any idea how to stop completely the belt slipping.
I attached a picture for the material.

Thanks
-Omar

 

[3DDave]

We need a picture of the installation, not the loose parts.

 

[Omar7amdi]

Hi 3DDave,
The installation looks like the picture in the previous post.

Thanks

 

[MikeHalloran]

The belt between the two pulleys is not perpendicular.

That alone bodes ill.

Did you read the engineering section of the belt supplier's thickest catalog? You should.

Or search for 'mule drives' or 'Corvair fan belt problems'.



Mike Halloran
Pembroke Pines, FL, USA

 

[3DDave]

A diagram isn't the same as a photo of the installation.

 

[Jboggs]

What kind of accelerations is the belt seeing in starting and stopping? Is it a steady even accel/decal or is it jerking? Sudden starts and stops can cause belt slippage.

 

[Omar7amdi]

Thanks for all participants.
We are looking for the cause, sometimes the pulley skips the belt during motion.

@MikeHalloran
Your idea perpendicular and looking at belt supplier's thickest catalog are good thoughts.

@Jboggs:
Same accel & decel.~0.43 rev/sec^2. & velocity is 40 rev/min. However, the belt sometimes skips
during motion.

 

[itsmoked]

I would, as suggested above, use a stiff spring under tension to mount the top pulley. Or alternatively use a torsional spring forcing an idler pulley against the back of the belt at the top to keep the belt tensioned during the accelerations.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Jboggs]

As suggested above, it is time to post some actual photographs or at least semi-accurate drawing. You have invested a lot of typing here when a few good pictures would answer a lot of questions.

Can you provide the actual spec on the belt (not just some generic description)?

 

[kjoiner]

Hello,

I would suggest changing from a trapezoidal tooth shape to one of the GT2 type belt configurations. I recently redesigned a belt drive somewhat similar to your application that used an L profile timing belt that skipped teeth under load. I switched to a 5mm GT2 design and also revised the tensioner idler to increase the wrap angle around the driving pulley. The increased number of teeth in contact dramatically reduced the tooth slippage problem. I agree with the other posts regarding idlers. You could be experiencing slippage on the slack side of the belt and as you mention, once slippage starts, it continues.

Regarding the post you mention, how are you guiding the trolley? Do you have shafts to maintain orientation of the trolley?

We really need to see some pictures of the assembly.

Kyle

 

[Omar7amdi]

Thanks for all,

@itsmoked

Similar to your suggestion, we tighten the belt. Great idea.

@kjoiner
What you suggested were done except changing from a trapezoidal tooth shape. We are planning to change to MTD (Metric Round Tooth).
how are you guiding the trolley? wheels on the corners.
Do you have shafts to maintain orientation of the trolley? Yes

For now we are using a trapezoidal tooth shape, with high tension on the belt. More than 36 hours passed and still working without
any slipping.

 

[itsmoked]

Here's a couple of typical torsional tensioners. Virtually ALL cars have them now so an extremely robust one should be inexpensive at any parts store.

See lots of applications here
See lots of applications here

Keith Cress
kcress -

http://www.flaminsystems.com

 

[kjoiner]

Hi Omar,

"What you suggested were done except changing from a trapezoidal tooth shape. We are planning to change to MTD (Metric Round Tooth)."

I've seen the MTD belt profile. Just make sure you are staying within the allowable specs for the belt. Also, make sure the tension in the belt is not going to cause excessive overhung loads on your drive train components, especially the plastic idler pulley at the top. Have you run through the design process for sizing the belt based on your loads. If not, York industries has a good design guide.

http://www.york-ind.com/

http://www.york-ind.com/York_ify_3.pdf

"How are you guiding the trolley? wheels on the corners. Do you have shafts to maintain orientation of the trolley? Yes"

Yes, we have two shafts running vertically along side the "box" we are moving up and down. The box has sets of rollers at each corner. At each corner there are two rollers. On the left side, the rollers are machined in sort of a spindle shape to surround the shaft and locate the box. On the right side, the rollers are similar but don't surround the shaft. They just keep the box located. I would show pictures but this is a part of a patented product. We originally tried using self aligning plastic bearings (like Igus) but the rubbing motion set up vibrations and made noise.

Kyle