Static Screw'TM Elevator Technology

Posted in: , on 22. May. 2009 - 20:30

Ajax Announces 'Static Screw'TM Elevator Technology

Increased application for screw elevators in solids handling

Solids handling and processing equipment specialist, Ajax Equipment announces new static screw elevator technology designed to increase the efficiency of elevators in processing industries.

Radically new concepts are rare for elevating bulk materials. However by reversing the basic mechanics of screw elevating such that the screw remains static and only the casing revolves, Ajax is able to deliver substantial benefits and operating advantages over conventional screw elevators. Click here to see a comparison of static and traditional screw elevators

The Ajax static screw elevator offers up to double the handling capacity on a like-for-like basis over current screw elevators. It also allows gentler handling of materials, reducing damage and attrition on friable and delicate products. The bulk material slides smoothly up the helical surface of the screw blade. There is no back-leakage in the flight tip clearance, thus avoiding the need to re-handle material that falls back as with a rotating screw.

The Ajax static screw also avoids the problems caused by agitating powders, often resulting in the material becoming fluidised or dilated, leading to control, density and packing problems and reducing hopper and bag capacity. Unlike conventional screw elevators, which work in a dynamic mode of operation, the Ajax static screw elevator can be used as a feeder with the outlet rate being controlled by varying the speed of the drive.

Ajax managing director Lyn Bates believes the static screw elevator will significantly enlarge the scope for the use of screws to elevate bulk materials. "The static screw approach opens up many new opportunities for screw elevators where materials can be elevated vertically over distances of up to 30 metres. It offers plant managers and engineers clear practical and process benefits designed to increase plant performance," he says.

Easier Elevator Loading

Amongst other advantages, the Ajax static screw elevator will pick up from a much lower level than standard screw elevators and collect from a larger area around the casing. Instead of fixed inlet chute, material can enter at any point around the periphery of the static screw. This means that the elevator can accommodate a feed intake much closer to floor level and with a larger feed hopper capacity for any given rim height. Moreover, the collecting mechanism does not offer the in-feed resistance that is generated by a rotating screw, so it will deal with less free flowing materials. Ajax also offers a mass flow form of feed hopper which can be used directly from the machines base for particularly difficult-flow materials.

Elevator Operation Performance Improvements

Static screw elevator technology will allow engineers to use elevators in situations where until now the length of conventional screw elevators has been limited by the stiffness of the centre screw shaft to prevent the screw making contact against the casing when running.

There is virtually no limit to the working length of the static screw because the stiffer casing can span greater distances between bearings, and extra bearings can be fitted if necessary; although Ajax recommends a practical working limit of 30 metres. In addition, the new Ajax elevator is not vulnerable to violent screw chatter or casing contact because the boundary layer of product stabilises the screw in a concentric position.

The physical attributes of capacity and length can make the static screw elevator an attractive alternative to bucket elevators and disc and wire type machines.

Easier Service and Maintenance

The drive on the Ajax static screw elevator can be located at any place between the inlet and outlet, where most convenient for maintenance, wiring, machine stability and supports and general access. A major servicing feature is that the bearings are external to the casing, so there are no seals or glands adjacent to agitated product. This has important operational benefits over conventional screw elevators where the bottom seal and bearing often give perennial leakage and maintenance problems due to the local churning of the processed material by the screw close to the bottom bearings and seal.

Broad materials handling application

The new static screw elevator is designed to handle bulk and solids materials from a wide range of industries including food and confectionery, iron, chemical, cement, mineral, detergents, plastics, animal foodstuffs, pesticides, agrochemical and coal.

For more information, please visit:

Figure 1: The AJAX Trial Machine Available for Demonstration or Hire


static2 (JPG)

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