ROTARY DRUMS – drive section

One of the most important components of a rotary drum is its drive section. Its most classic form is an open gear driven by an electric motor through a reducer. While the spatial relations between the engine and the reducer, between the gears of the reducer on its individual stages and between the reducer and the pinion are quasi constant, the position of the axis of the gear rim in relation to the position of the pinion is unfortunately not constant feature.
The change in the position of the gear rim results from factors such as:

• thermal expansion of the rim, which is a detail of considerable dimensions, and therefore changes its diameter even at small changes in temperature, where the increase in the temperature of the rim results in the reduction of clearances on the meshing of its teeth with the pinion teeth,
• crank of the geometrical axis of the shell on which the gear rim is mounted, which may cause synchronous, radial run-out of the element mounted on it, and thus a synchronous change of clearances on meshing with the pinion as a function of a single rotation of the object,
• the diameter of the drum shell, which changes its dimension as a result of temperature changes, causing a change in the position of the axis of rotation in relation to which the gear rim rotates,
• wear of the raceways of the live rings and support rollers, which in the long term induces the lowering of the position of the drum axis, and thus causes the axis of the gear rim approaching the axis of the pinion.

Effects of changing the position of the gear rim

Changing the position of the rim, and in particular reducing the distance between its axis and the axis of the pinion, results in the reduction of tip and backlash clearances, which in extreme situations can be minimized to values at which there is a risk of mutual jamming of the teeth of both wheels (lack of clearance). Such jamming, in an extreme situation, can lead to tooth breakage, which should be considered a very serious failure.
In addition, the uncontrolled reduction of the tip clearance is very often the cause of an increased level of vibration, because it results in the contact of the tooth tip with the previously unused (unworn) surface of the tooth, located right next to its groove. These vibrations, introducing very high dynamic loads, can also lead to damage to the teeth as well as to other elements of the drive section, such as pinion bearings, or elements fastening the gear rim to the shell of the drum.

Preventing the situation of too low tip clearance in the open gear

The simplest way to prevent the occurrence of a situation of too small tip clearance in an open gear is its periodic inspection with the frequency adequately selected to the expected rate of change.
Measurements of clearances, however, are not easy to carry out during the operational movement of the object and without the possibility of stopping its operation.
For this reason, and taking into account the importance of this parameter and the possible consequences of not maintaining its value to the necessary extent, ZMP engineers have developed a simple and, on the other hand, effective device / system for continuous measurement of the relative position of the gear rim’s tooth tips, so as to be able to detect in advance the situation of too small clearance on the meshing of the teeth of the gear rim with the teeth of the pinion.
The device consists of a control box, powered by 230V~, equipped with sound and light alert emitters and a GSM module, with the help of which additional one-way communication with the interested party takes place using SMS messages.
An integral element of the system is a sensor which, with the use of a specially designed handle, can be easily moved closer to the teeth of the gear rim to the distance that the user deems appropriate, and the system, after reduction of this distance by the set value, immediately reacts, informing users with sound and light signals (directly on site) and by sending an SMS message to the declared telephone numbers.

Advantages of the system

• immediate information about the decrease of the tip clearance by a predetermined value, via SMS message,
• possibility to add up to four telephone numbers to which SMS alerts will be sent,
• the ability to disable SMS alerts for a given time - independently for each user,
• emission of a light and sound signal directly on the facility, with the option of turning off a given signal independently,
• simple installation and use as well as effective and trouble-free operation,
• the ability to "plug" the device into the DrSmart system.

More information about the system can be found in its user manual. If you are interested in the product - please contact us. We will provide more information and present an up-to-date price offer.