Re: Drive System For A Rotating Kiln
More info on the backstop. I do not see a reason for the backstop as when the inching drive is engaged the unit is not going to roll back. Now, when doing maintenance and a the unit needs to be crept a little to change refractories I see a need for something to hold the unit and not let it roll either forward or back, is this correct? ■
Re: Drive System For A Rotating Kiln
The backstop the manufacturer is recommending will be a simple sprag clutch. With that arrangement the inching drive stays connected all the time. When the main drive stops the kiln load will not be able to contra-rotate the shell & the whole bag is held until the inching drive kicks into life. With an electric motor you can start against load whereas with the suck, squeeze, bang & blow engine you did need a clutch.
The kiln is not likely to roll forward; otherwise you wouldn't need any drives in the first place? To hold the machine really solid, when required, you just need to jam a hard pin in between the ring gear & pinion. Any old excavator track chain link pin is ideal. ■
John Gateley johngateley@hotmail.com www.the-credible-bulk.com
Re: Drive System For A Rotating Kiln
When a low speed inspection drive is required, the use of a low speed geared motor connected to an extended intermediate shaft in the main gearbox through a sprag clutch is an efficient and safe solution.
Unlike the use of a standard clutch there is no need for an engage/disengage system of the required safety interlocks.
Should both drives be running at the same time the sprag clutch just over-runs with no damage to the inspection drive unit.
I came up with this arrangement with a gearbox sales engineer some 25 years ago (though we make no claim to originality) for large high speed bucket elevators which have run sucessfully since. Prior to this I had only ever seen dog clutch arrangements. ■
Drive System For Rotary Kilns
Is there anything else we should take into account?
YES; Safety.
The reason a backstop is required for an auxiliary drive is to protect the auxiliary drive from kiln roll-back when it is stopped. A kiln that is allowed to freely roll back (it will do so because the load in the kiln will drive it backwards) while the auxiliary drive is engaged will cause the inching motor to be driven backwards at very high speeds. This will damage the drive and in some cases has cause the drive to explode from centrifugal force. This is a real danger.
The backstop has both an electric and manual release and governs the roll back speed.
As far as an inching drive clutch is concerned, a manual jaw cluth is all that is required.
Walter Gebhart
Phillips Kiln Services Ltd. ■
Re: Drive System For A Rotating Kiln
Although not mentioned, my inspection drive incorporated a brake motor (with manual release) to provide the necessary hold back feature for the full load, thus avoiding the need for a manual clutches. ■
Drive system for a rotating kiln
We have been asked to replace a drive system for a cement kiln, the actual drive system consists of an electric motor coupled to a gear reducer coupled to the kiln. The system also has an inching drive which is done via a internal combustion engine that is engaged to the high speed shaft of the gear reducer, this inching drive is conected via a manual clutch.
We have been asked to change the gear reducer as the customer has already chosen to go with a variable speed drive and an 1800 RPM electric motor, these two items have already been purchased.
We are planning to install a new gear reducer (300 HP) with a safety factor of 2 (this is what we have been told to use by the gear reducer company we work with)+ an inching drive consisting of an electrically actuated gear reducer (15HP).
The inching drive has to be disengaged while the unit is in normal operation and engaged only when the main drive is disconnected.
My questions are as follows:
We are planning to install a clutch to engange and disengage the inching drive, is this the best way to proceed and which type of clutch would be the least expensive one for this type of operation?
We have been told by the clutch manufacturer that we will need a backstop, the current unit does not have a backstop so I would like to know if we now have to install a backstop.
Is there anything else we should take into account?
I await your comments. ■