Re: Bucket Elevator Problem
Originally Posted by DRKREDDY
• 1440-1400 chain swing as earlier and hitting to casing
• 1350 RPM just leaving small gap from casing
• 1300-1200 just maintaining the gap of 20 to 30 mm between casings to chain
• 1200-1100 about 40 mm gap maintaining but still swinging
• At 1000 RPM and Less ,the chain swing (side wise) was minimized about 50 mm gap maintaining ,but bucket tips are started hitting to casing in other direction
With above observations we concluded that, the elevator can be operated between 1100 to 1200 RPM and can be meet our requirement too.
Basically the chain pitch provided by your OEM was too long. ■
Re: Bucket Elevator Problem
TO DRKREDDY :
The sprocket wear(Within 15 days of operation) is a symptom of a deep rooted problem.By installing a VVVF drive you have managed to reduce the chain swing but not totally eliminate it.Moreover reducing the sideward swing has increased the " TO & FRO " swing.
The sprocket wear is a strong indication of your root problem(Chain Swing) and unless totally eliminated, it will continue to manifest in other ways.
Instead of diverting your attention to sprocket wear, I suggest you focus on the root problem and rest will follow suit.
I would like to know whether you have checked for Resonance as Mr. Teus Teuninberg had pointed out earlier.
You have expanded the casing by 180 mm once and now you have also installed a VVVF drive but the root problem is still very much existent.
The elevator design,installation and ambient circumstance need to be scrutinized from scratch.
Baiju Joshi ■
Elevator Problem
Dear Designer,
With all support we tried to manage the sutuvation till date ,now by redusing speed of elevator and selecting heigher hardness of sprocket (most equelent to chain bush hardness) we rechead to get service life of sprocket 3 to 4 months continues oparation at 75% load
in our site we have single strand elevators for lime stone handling having capacity of 25 TPH in which the head sprocket of elevator is similar to boot sprocket ie plain ring (insted of walking tooth) presently this could oparating satisfactorly
This type of system can be used for Double strand? any ware any body used? if so up to what capacity to what capacity can be used,request you to sugest.
Regards ■
Re: Bucket Elevator Problem
Chain and bucket elevators take various forms.
The chain may be "round link" type (common in Europe), cast short pitch chains, or long pitch "engineered chain" (common in the USA).
There may be a single strand of chain, or two strands.
The driving head shaft may be provided with a toothed sprocket for a positive drive, or a plain diameter wheel for a friction drive.
It's a matter of application and preference in individual cases.
The "advantage" of a toothed sprocket is the positive drive requiring a minimum of chain tension. The "disadvantage" is that as the chain wears the pitch gets longer and the engagement with the sprocket deteriorates leading to rapid sprocket wear.
The "advantage" of the plain diameter wheel is that since there is no positive engagement it is tolerant to increases in chain pitch. The "disadvantage" is that additional chain tension can be required to ensure the correct tension ratio across the wheel to ensure a friction drive. ■
Re: Bucket Elevator Problem
Thanks for clarification,in our case using engineered chain 12 inc (FLAT) pitch double strand having ,Head sprocket R4251-8T-765 PCD and ,Bottom traction wheel 737 mm OD oparating cpacity was 5TPH/Hour another one is 75TPH /Hour the bottom trction weel is equiped with VGT
Request you to sugest me,for above metioned requierments it is advisable to change Head sprocket as round rim insted of Toothed one
Regards ■
Re: Bucket Elevator Problem
You need to get an engineer to look at your machines as they are and do the nessary calculations.
But frequently with robust steel chains and buckets a friction drive is a viable option with chain and bucket elevators. ■
Bucket Elevator Problem
Dear Friends,
Recently we commissioned the coke calcification plant in Kuwait,in our material handling system have had a double strand bucket elevator which specifications are as follows
Now let me explain the problem we are facing Please bear with us, if some of the following is already common knowledge to yourselves, as we are not yet sure of your specific familiarity with the designs as they apply to the equipment.
Bucket elevators are unique to the service of Material Handling However In our case right from trail runs we noticed that Chain is getting swing and causing for casing damages due to continues rubbing on to casings especially at 2/3 of height from boot
Swing of chain may have variety of causes. Incorrect specification or poor quality of suppler tolerances, poor alignment practices
We reported the problem to OEM and subsequently studied the same and reverted back with a proposal of Head sprocket assembly replacement and adding of up to 500 kg Counter weight at bottom take-up and thoroughly checked all the key alignment factors found them selves satisfied, but problem not solved.
At this time, OEM and sub contractors (supplied) it must be pointed out that the factors above are divided among several entities for their design, installation and subsequent warranty. No single entity is willing to accept major responsibility for the failures that have occurred, each pointing to the other as the primary culprit. As expected, the issue has become extremely contentious.
We had already extended the casings by 180mm to avoid rubbing action almost 40 meters height, now the elevator is operating with lot of swing ,but continues rubbing was minimized
I hope this information is adequate to advise us for corrective action as well as probable causes for such discrepancy
Request any of viewers could advise me for further action towards resolving the problem and share your experience…
Thanks for your time
Regards ■