Re: Air Conveyor/Hold Back Clutch Problems
Bustin
Increasing lift will increase horse power requirements and also increase in torque holding requirements for your holdback.
Your entire system needs to be thoroughly analysed when you increase lift. Reducer mechanical and thermal rating, belting, pulley shafts, bearings, etc, etc. It can get complicated and you may not be able to get all your answers in here.
Is your holdback internal/external to the reducer or is it a separate unit mounted on a pulley shaft?
We may be able to give you genaral answer that could lead you to a solution so any info is helpful. Minimum requirements are listed below.
- Horizontal center to center distance of head and tail pulleys.
- Total lift.
- Belt speed.
- Motor HP.
- Gearbox size and model.
- Backstop \ holback size and model.
- Specs on material being conveyed.
Another thing to look for is the type of oil being used in the clutch. Sprag clutches do not like EP based lubricants. Check to see if this has been changed recently. I have seen this happen much too often. Always go with the manufacturers recommended lubricant.
Hoping to help,
Gary Blenkhorn ■
Gary Blenkhorn
President - Bulk Handlng Technology Inc.
Email: garyblenkhorn@gmail.com
Linkedin Profile: http://www.linkedin.com/in/gary-blenkhorn-6286954b
Offering Conveyor Design Services, Conveyor Transfer Design Services and SolidWorks Design Services for equipment layouts.
Re: Air Conveyor/Hold Back Clutch Problems
Hi Gary,
Ours is an external hold back, mounted on the shaft. And has uses grease and oil as lubricate.
I will get the rest of the information as soon as I can and post it back.
Thanks for the help ■
Re: Air Conveyor/Hold Back Clutch Problems
Bustin:
It sounds as if your air glide conveyor was either inappropriately designed or installed. That being said, you have inhereted the problems.
The hold back should not wear rapidly as it should only engage once the drive has stopped. If it is engaging prematurely, check your control circuits and/or program (if using PLC). Also, check the hold back clutch clearance - it may be set too close.
As far as the belt lift is concerned, this is a major problem that sound like a design issue (assuming that you have checked and eliminated any leaks). This issue should be addressed by the conveyor supplier.
Good luck with the troubleshooting! ■
Re: Air Conveyor/Hold Back Clutch Problems
It sounds as if your air glide conveyor was either inappropriately designed or installed. That being said, you have inhereted the problems.
Hi Dave,
Let's just say you have a good insight into our situation. 
When the airbed was installed we were using "plc" but since have gone to a new program called "foxboro". But it doesn't monitor the holdbacks at all. But I am checking to see if the motor amps can show anything (holdback slightly engaged and causing drag). But foxboro overwrites itself, so that may not be possible to check from past readings.
The holdback is a marland and I am checking on the lubricants that we use to make sure they meet the specs. (thanks gary)
I am also still tracking down the details to post here.
Thanks for the input, it is greatly appreciated. ■
Re: Air Conveyor/Hold Back Clutch Problems
Bustin
Here is a link for a Marland Backstop manual in PDF. I am assuming this is the style you are using. This literature gives you the recommended lubricants and the warning (as I said earlier) about EP additives as well as the do's and don'ts on installation and maintenance.
http://www.marland.com/literature/pdf/P-1346-1.pdf
Good luck
Gary ■
Gary Blenkhorn
President - Bulk Handlng Technology Inc.
Email: garyblenkhorn@gmail.com
Linkedin Profile: http://www.linkedin.com/in/gary-blenkhorn-6286954b
Offering Conveyor Design Services, Conveyor Transfer Design Services and SolidWorks Design Services for equipment layouts.
Re: Air Conveyor/Hold Back Clutch Problems
Hmmm, I think I am going to break these problems in to 2 groups. Since our holdback is down and we are waiting for a replacement, I'm going to concentrate on it first. (because we do NOT need to do this again)
The attachments are of the holdback that failed after 2 months. I didnt take the pictures or see the holdback in this condition. I was off at the time and when I returned it had been removed to the warehouse.
http://www.wtv-zone.com/BooWorks/imgs/3chb1.jpg
http://www.wtv-zone.com/BooWorks/imgs/3chb3.jpg
And Gary thanks for the pdf file, I have been reading it. And I may blow it up triple size and have it lamented and posted on all of our holdbacks.
From the lubrication charts at work, we use Precision AW-68 when we change the oil or add oil.
I noticed in the help file that Gary posted a warning that grease SHOULD NEVER be used for internal lubrication.
I shudder to mention this, but 4 weeks ago a new employee pumped so much grease into the holdback that it was coming out around the shaft in the front and out of the keyway and dripping on the floor.
I had it shut down and the dayshift maintaince was to check it to see if seals were blown and needed to be replaced. I do not know what was found but the next night it was in service again.
Could grease getting somewhere it should not have and mixing with the oil caused this?
Oh and any suggestions for headache medication from troubleshooting during Christmas would certainly be picked up at the nearest Walmart in the morning.
The motor that drives this beltline: Westinghouse 350 hp, 4160 volts, 1186 rpms
Gear reducer: BradFoote GearWorks size KD300FF, input rpm 1170, ratio 9,30-1
Clutch: Marland 63MA
And we move coal and a lot of it. 30,000 tons per day
Thanks Gary and Dave for the input and the help. ■
Re: Air Conveyor/Hold Back Clutch Problems
Bustin
It looks to me that you have blown the labyrinth seals with too much grease. The grease is only used to fill the labyrinth to prevent contaminants from getting inside. There should be a grease reflief fitting in the unit which may be blocked. Ensure that the grease is being purged through this fitting.
Contamination into the oil from the grease can very well be the cause of your failure.
As far as the medicine that you need for your headache all I can say is "Been there done that" I know that's not what you want to hear but we all face these things from time to time. Just poor timing for you.
Good luck and keep us posted to your progress. It is always good to hear results.
Gary ■
Gary Blenkhorn
President - Bulk Handlng Technology Inc.
Email: garyblenkhorn@gmail.com
Linkedin Profile: http://www.linkedin.com/in/gary-blenkhorn-6286954b
Offering Conveyor Design Services, Conveyor Transfer Design Services and SolidWorks Design Services for equipment layouts.
Re: Air Conveyor/Hold Back Clutch Problems
Hi Gary,
I'm on vacation starting Saturday, and by the time I get back they may have put in a new one and blown it up too. Poor maintaince practices (over lubing just as bad as under lubing) and other issues with this one belt line is really costing us in downtime and temporary fixes.
We have 10 hold backs but this one beltline (airbed), has gone thru 4 holdbacks in the 16 months.
Finding out it was from over greasing would be good for me, I could move on to the airbed part and get it to tote a load.
I'm pulling checklists and service records now to see how often our operators were greasing the previous holdbacks on this beltline.
You have a great evening, and I may have to send you and Dave a turkey or ham for the help. ■
Re: Air Conveyor/Hold Back Clutch Problems
Bustin:
As Gary has indicated, your most likely cause for the holdback failure is with grease contamination. You can determine if this is the cause by examining the failed unit after it has been removed. If grease is mixed in with the oil, overgreasing and blown seals are the likely culprit. To get around this in the future, a training program for your skilled trades is in order - along with a listing of proper maintenance procedures. Conveyor service companies, technical writers/trainers, consultants, or the original equipment suppliers should be able to help with this.
As far as the lift (support) problem is concerned, do you have any other units on site that are functioning properly? Often a direct visual comparison between what works and what doesn't can give insights into possible corrective actions. Also, I would try to deflect the problem to the manufacturer and installer - they may have experienced similar problems elsewhere.
Regards and good luck in 2006. ■
Re: Air Conveyor/Hold Back Clutch Problems
Hi Dave,
I am on vacation this week, but they are installing a bigger holdback clutch today. (throwing more money at it)
I will be back at work Saturday morning and my first stop will be to look at the new one. And hope they didnt overgrease it.
We have had no trouble with any other holdback clutch, they have been in service for years. But all of those are "Falks".
But this one is on the air conveyor. And this is the 4th one to date.
I will check into the service plans and details as soon as i get back.
Thanks for all the info and things to look for. It's invaluable and will save us money and downtime in the future.
We are going to have more airbeds put in on the other beltlines, and we are going to do them right. So finding the answers to this beltline's problems is paramount so we don't repeat our mistakes. ■
Air conveyor/hold back clutch problems
Good Morning Forum,
This is my first time ever in here and found it while "googling" air conveyors. But in my short time in here, I have noticed the wealth of knowledge and experience in here.
We have a problem with a hold back clutch receiving extreme wear and finally failure (2 times in last 90 days).
This problem has been given to me to trouble shoot. (Early Christmas gift from my boss)
This air conveyor has been a problem since day 1. Trips out often from over current (over amping over the set limit). But the problem is not from excess weight on the belt. Its caused by the belt rubbing the table because of inadequate lift from the air blower. (another issue)
This is a 48 inch belt rated at 1400 tph, but because of the lack of lift we run 1200 tph on it, but still have the trips. (PRB coal)
At work you can't get straight, honest anwers for solutions because of "my turf" issues. (don't even ask)
(1)What can we do to increase the lift on the conveyor so we can run the rated tonnage. (already increased blower horsepower)
(2)And how can we safeguard and/or improve hold back clutch life.
So here I am, so anyone that wants to help. I sure could use the advice.
Any details U may need. (motor hp, air blower hp, belt length, gearbox setup, conveyor angle) let me know and I will get it.
Thanks in advance and I wish everyone a Merry Christmas and a Happy New Year. ■