Belt and Pulley
Belt and Pulley
(OP)
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
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





RE: Belt and Pulley
John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Belt and Pulley
Here is a drawing.
RE: Belt and Pulley
STF
RE: Belt and Pulley
RE: Belt and Pulley
Thanks it's a good idea.
I added the bottom roller only, where the motor pulley. But I did not add the top one. By the way the upper pulley
has no teeth, it's a roller. But the motor pulley still skips the belt teeth sometimes and as soon as start skipping it stays doing it.
RE: Belt and Pulley
The object is a trolley. Both belt ends are fasten on the trolley. The trolley carries 10-20 lb rod.
RE: Belt and Pulley
Unless you need the carriage to move _very_ fast,
you need a gearmotor, and/or a variable speed drive.
If there's any risk of anyone getting hurt, and it sounds like there is,
you need to get an actual engineer involved.
Mike Halloran
Pembroke Pines, FL, USA
RE: Belt and Pulley
Yes I'm using a gear with a variable speed. The speed plays role in the problem occurrence. It takes more than 3 hours ,continuous running, before the problem occurs. As soon as it occurs it keeps continuous occurring. The trolley out of sync with the motor rotation.
Thanks.
RE: Belt and Pulley
1. Belt oscillation during rapid travel is allowing a "slack" wave to ride around the motor pulley.
2. The belt is under-rated for the loading applied.
Either way, two idlers at the drive pulley will help by increasing wrap angle on the drive and isolating it from oscillations.
je suis charlie
RE: Belt and Pulley
RE: Belt and Pulley
John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:
The secret of life is not finding someone to live with
It's finding someone you can't live without
RE: Belt and Pulley
RE: Belt and Pulley
RE: Belt and Pulley
RE: Belt and Pulley
Adding onto the excellent suggestions posted above, have you run through the process of sizing the belt - selecting the profile and width? Some of the newer profiles such as the GT2 etc. are better at resisting slippage than the trapezoid types. What is the distance between the drive pulley and the idler pulley? How many teeth do you have in contact on the drive pulley? What are your torque and power requirements?
I would recommend contacting some of belt and pulley manufacturers to get their input as well - Gates and York Industries are a couple that come to mind. I would also recommend using a timing pulley at the top idler position since there are teeth riding on it. It will be quieter and is more appropriate. If you do use a timing pulley at the top, make sure your are spaced an integral tooth count apart. You can use smooth rollers as tensioners since they are running on the back side of the belt.
Kyle
RE: Belt and Pulley
RE: Belt and Pulley
Do you know whereabouts in the stroke of the system it starts to skip? If it happens at the bottom, it could just be the stretch in the belt feeding too much slack into the drive pulley. If you think this is happening, you might add a tensioning spring to the belt attachment on the bottom of the platform.
A.
RE: Belt and Pulley
RE: Belt and Pulley
I have to add this.
The post that carries the trolley between point A and B is not perfect, straight. The distance between A and B is 300 cm.
When I put a laser light at point A to pint at the wall, by the time the trolley at point B, the laser light deviated by 15 cm.
The light should remain vertical " perpendicular " , at right angle.
Distance from A to B = 300 cm; deviation ~= 15 cm.
RE: Belt and Pulley
RE: Belt and Pulley
By the way, I'm an electronic engineer working with a mechanical engineer.
Thanks
RE: Belt and Pulley
Mike Halloran
Pembroke Pines, FL, USA
RE: Belt and Pulley
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
RE: Belt and Pulley
RE: Belt and Pulley
The installation looks like the picture in the previous post.
Thanks
RE: Belt and Pulley
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
RE: Belt and Pulley
RE: Belt and Pulley
RE: Belt and Pulley
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.
RE: Belt and Pulley
Keith Cress
kcress - http://www.flaminsystems.com
RE: Belt and Pulley
Can you provide the actual spec on the belt (not just some generic description)?
RE: Belt and Pulley
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
RE: Belt and Pulley
@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.
RE: Belt and Pulley
See lots of applications here
See lots of applications here
Keith Cress
kcress - http://www.flaminsystems.com
RE: Belt and Pulley
"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