Twin Motor Spiral Elevators

Application

Twin Motor Spiral elevators are designed to elevate bulk materials using a minimum of floor space, however, because of the helical trough design, the resultant conveying time is such that it enhances other process operations to be carried out, e.g. cooling, heating, drying etc. these units also handle the product gently and are advantageous when product breakdown may be caused by more conventional conveyors. Another advantage is that the feed rate is constant and not one of constant surges. Capacities up to 13m3/hr can be obtained, when handling free flowing granular materials.

Mode of Operation

Two out of balance vibrator motors are mounted on the same horizontal axis, opposite and at 90 ° to each other. the resultant vibration action conveys the bulk material on a rising helical path about a vertical axis.

Construction

The elevator comprises:

1. A helical conveyor section, which includes a fabricated helical trough, center tube and infeed dish, onto which is mounted two vibrator motors.
2. A fixed section, which includes a fabricated central mast .

The helical conveyor section slides over the fixed section and the two are connected together via bonded rubber anti-vibration mounts at the top and bottom.

Helical conveyors can be supplied with elevating heights of up to 7metres and diameters of 340, 560, 680 and 900mm.

The vibrator motors are normally mounted beneath the input dish, however if the discharge point into the elevator is too low to permit this then the motors can be mounted at the top of the elevator structure. A totally enclosed construction can be achieved either by fitting covers to the helical section or by encapsulating the whole elevator with a free standing enclosure.

Control Units

Spiral Elevators of this design are normally operated by means of a two motor starter unit. This connects both motors direct to the mains supply simultaneously and provides interlocked overload and single phase protection for each unit. When a twin motor spiral elevator is switched off a temporary increase in amplitude occurs as the motors slow down and pass through the resonant frequency of the suspension mounts, but this can be minimised by incorporating d.c. injection braking.

Specials

Although our standard range of elevators are driven by out of balance vibrator motors, which give a fixed throughput, we can offer units with inverter based controls or electromagnetic drives where the throughput rate is to vary. An alternative to this is to employ a twin motor type spiral elevator and use a small electromagnetic drive vibrating feeder to charge the elevator at a variable rate. Cooling, heating and drying can be achieved by having a double base in the helical trough which can carry water, steam or hot air.