Rolling Along.
Hi Narayanan,
Previous threads on this topic are also useful. Conveyor rollers are subject to similar rules as automobile wheels where camber, castor and toe-in are vitally important. I am not aware of any mathematical study on the behaviour of garland and fixed idlers along a horizontal curve where the outside is moving very slightly faster than the inside. Some forum members dismiss this state of affairs. Until there is quantification of the subject we have to admit that, as is often the case, we don't know. I would ask, is yawing misalignment built in when it comes to garlands along a curve? I honestly don't know because I have only ever used garlands as a gap stop at the entrance to travelling trippers where they are very useful.
Any savings in installation cost are probably founded on the scaffolding poles used in the structure. I never notice any scaffolding clamps used to locate the garland idlers and that concerns me. I would think that if the power comsumption is higher and if the bearings are identical then the extra power is dissipated at the idler/belt interface. Using more shorter rollers might alleviate the situation but then the cost of extra bearings nullifies the CAPEX although it should reduce the idler OPEX but that was not the original intent of the thread. ■
John Gateley johngateley@hotmail.com www.the-credible-bulk.com
Re: Garland Idlers.
Hello,
Firstly simple question like whether fixed frame idlers are better / superior or garland idlers are better / superior has no relevance. Both are useful and so they are in use.
Garland idlers advantages / application is as below:
1) Garland idlers are flexible and adjust conveyor frame internal deflection (distortions). So they are ideal for shiftable conveyors.
2) Garland idlers are light in weight and use of quick release link makes the idlers disengagement from the belt, and its replacement very easy and quick. Belt do not hinder its replacement.
3) Garland idlers are suitable for practically horizontal conveyor or portion of conveyor which is horizontal. The idlers swing forward due to belt drag when conveyor is running. This results into side roller backward tilt by approximately 1.5 degree, say 2 degree for power calculation purpose. So extra power due to garland idlers will be corresponding to as if side rollers have 2 degree backward tilt, when conveyor is horizontal. The tilt resistance is same whether the tilt is backward or forward.
4) Deeper trough helps in aligned running of belt against backward tilt under dynamic condition.
Sr. no. 1 is necessity for garland idlers. Some users are happy with quicker replacement of idlers and less maintenance cost in spite of some more power. So they will prefer garland idlers (when conveying system is long and there are thousands of idlers). Some buyers give more importance to power saving and they will opt for fixed frame idlers. Thus idler choice for horizontal conveyors depends upon the perception of the buyer. For usual in-plant conveyors, the practice is to use fixed frame idlers. The practice has certainly come after long time experience and one should give proper investigation and thought, if one wants to deviate from that.
Ishwar G. Mulani
Author of Book: ‘Engineering Science And Application Design For Belt Conveyors’. Conveyor design basis ISO (thereby book is helpful to design conveyors as per national standards of most of the countries across world). New print Nov., 2012.
Author of Book: ‘Belt Feeder Design And Hopper Bin Silo’
Advisor / Consultant for Bulk Material Handling System & Issues.
Pune, India. Tel.: 0091 (0)20 25871916
Email: conveyor.ishwar.mulani@gmail.com
Website: www.conveyor.ishwarmulani.com ■
Re: Garland Idlers.
Hello,
Referring to my earlier posting; the idler replacement implies A) Rollers replacement in case of fixed frame idler set B) In case of garland idler; set of 3 rollers connected by links, and end suspension up to the fixed hook.
Ishwar G. Mulani
Author of Book: ‘Engineering Science And Application Design For Belt Conveyors’. Conveyor design basis ISO (thereby book is helpful to design conveyors as per national standards of most of the countries across world). New print Nov., 2012.
Author of Book: ‘Belt Feeder Design And Hopper Bin Silo’
Advisor / Consultant for Bulk Material Handling System & Issues.
Pune, India. Tel.: 0091 (0)20 25871916
Email: conveyor.ishwar.mulani@gmail.com
Website: www.conveyor.ishwarmulani.com ■
Garland Idlers.
Dear Friends,
I remember to have seen a thread,where in it was mentioned that for fixed conveyors Garland idler is not recommended,due to
Higher power conception, mis-tracking and higher maintenance cost.
I have also seen in some installations where mistracking and higher maintenance costs are posing problems.
Theoretically higher power cost should be there.
Still many new installations prefer garland idlers, claiming that the initial installation cost is less.
If any expert has practical datas to establish the higher power cost please share with the members of the forum.
Comparative study details of initial installations can be calculated,but if any member has it please share.
Rgds,
Narayanan Nalinakshan ■