Differences in spiral conveyor systems: why drum-free?

Spiral conveyor provides automation of production processes, increase profitability and saving of production space. These conveyor systems have already gained its popularity among food producers. However, the engineering idea does not stand still, and has moved far ahead. Historically, the first was a development of a system with drum drive, which later has been changed and evolved.

Drum spiral conveyor

Spiral conveyor of this kind is made of modular belt that twisted around of special drum structure in the center. The belt is sliding on rails with plastic profile with low friction.  The rails are fixed on external vertical support columns. The drive drum has a cylindrical shape and made of profiled pipes or plates, forming a continuous or rarefied surface.

Movement of the drum can be carried out directly from gear motor or by means of a  chain transmission (chain drive causes additional maintenance costs). In drum spiral conveyor the belt is moving due to friction forces (the so-called friction drive) arising as a result of tightening the belt around the drum. The drum has no teeth, accordingly, there is a danger of slippage. To prevent slippage the belt should be correctly tightened.

Extent of tension of the belt is an important component, as required to comply with uniform tightening the spiral in order to avoid the effect of “collapse”. This problem requires additional gear motor (on the output of the spiral conveyor) that supports a desired amount of tension. Both gear motors should be equipped with inverters for tension adjustment. In addition, belt tensioning feature is that if you to pull over the belt, it goes up and folds up along the drum, or simply brakes.

This drive drum execution has a high rigidity but also great restriction on the configurations, as it can support only a round shape with a single belt.

Spiral conveyor with external drive (drum-free)

Thanks to the experience gained during operation of the spirals with driving drum, as well as a fresh look at the design possibilities, was developed a completely new type of spiral conveyors – with an external drive. The drum was removed and drive was converted to a system situated externally of the conveyor belt. New drive system has been implemented as a stainless steel structure with a gear motor located in a bottom part and connected with a vertical shaft that has driving sprockets, the number of which equals the number of tiers on the spiral conveyor. Belt received the teeth on the outer contour and through which carried out the movement from the sprockets, thus forming a multilevel gear transmission.

The supporting structure has remained the same: vertical columns (legs) and mounted on their rails for belt sliding. Because the design has lost the drum, it has become lighter and easier.

For best durability, the inventors abandoned the use of plastic belts. The choice was made in favor of stainless steel welded modular belt. To ensure a low coefficient of friction of the steel belt on plastic rails, it was decided to use the special sliding elements on the sides. With these elements, and thanks to innovative technology of external drive system, the belt now has not only excellent slip, but also a unique opportunity that is able only for spiral conveyors of this type – a phenomenal flexibility.

Features of the spiral conveyor with an external drive, compared with other types

The organization of the production process, as if the freezing, cooling, proofing or pasteurization, will be the most beneficial to use a spiral conveyor, placing it in the cell with the required climate conditions. It will save space, increase the speed and profitability of your production. As we have seen, there are different designs of spiral conveyors, and the crucial role here plays the way of the organization movement of the conveyor belt. For comparison, consider the model of the drum type and model of the external drive tiers DLS-EVO.


Drum drive system imposes limitations on the spiral shape. It can be only in form of a circle with descending or ascending spiral. Placing of input / output sections to each other may be at an angle of 0º, 90º, and 180 º. Options for directions and height are limited. Changing the configuration is only possible to increase the number of spirals mounted one by one.

Models with an external drive do not have a drum, and therefore do not have such restrictions. This allows a wide range of configurations. The shape can be round or oval, the input / output sections placed at any height and in any part of the conveyor. It can be mounted around the columns. This is suitable for any type of customer’s building, especially with complicated configuration.


Drum system allows to control only one conveyor belt and can not ensure the simultaneous transportation of multiple different products. DLS-EVO model with external drive is fully capable to create a multi-belt conveyor. Thanks to a model features, it is possible to drive up to four independent spiral conveyor belts in a single structure. Each belt can move at different speed, thereby making it possible to provide different resting time for different products


Usually in the drum spirals to reduce the cost and weight of conveyor used a plastic belt. The belt of this type is easier to install, but has a low durability and tends to break.

The spiral conveyors by Millennium Engineering applies modernized belt type. DLS-EVO belt is a patented know-how and made thanks to an electric fusion of bars 6 mm diameter to a special very strong chain with step 32 mm on which there are profiled teeth welded in 4 points for absolute mechanical resistance. All parts are made of stainless steel AISI 304. For small product handling there installed special plastic mesh which is optionally could be changed for stainless steel mesh up to customers request. Due to side sliding elements (wings) belt is securely held on the guides and does not have collapse risk common for drum systems.


Because of the design, the width of belt in drum spiral conveyors is limited in the range of 400-1000 mm. This is due to the fact that thinner belts have a higher risk of collapse, and wider belts have much weight, and therefore the console mounting of the rails only to external support can not guarantee the reliability of the structure.

The spiral conveyor with external drive DLS-EVO has rails mounted like beams: to both external and internal support columns. When the belt is securely fixed on rails, it allows to have a wide range of belts from 250 to 1300 mm.


Spiral conveyors with drum drive due to the features of their design have increased metal consumption, and as a result a great weight. This load together with additional equipment and weight of the product often requires special preparation of the floor and bearing structures.

On the contrary, conveyors with external drive in the absence of internal drum, have a weight of 1.5-2 times less. This will not only lower the requirements for the placement of equipment, but also a has a smaller inertia: conveyor easier and faster to heat or cool, which allows the production to work more flexibly and at lower costs.


Internal drum is not only a central drive unit, but also a storage for various contaminants. It is located inside of the structure, making it difficult to access and increases labor costs for its cleaning.

Without of internal drum, conveyors with external drive have no such problems. Most of the structural elements have rounded shapes and 100% available for cleaning. (our hygiene philosophy)


Spiral conveyors with drum drive have many mechanical parts that are prone to wear. At the same time, carrying out maintenance is labor intensive and expensive. For drum repair must be practically dismantle the entire structure.

Spiral belt conveyors with external drive have 2 times less mechanical parts to wear, all current types of repairs are carried out very simply and cost-effectively. In order to replace one gear, you just have to remove few screws and replacement of plastic side element on the belt should be in a few seconds.


DLS-EVO conveyor systems with external drive is a very competitive product even though their objective advantages. Millennium engineering monitors the market and guarantees to its customers at least 10% benefit in price in relation to other producers. As well the operating costs of the of this spiral conveyor is 30-50% lower than analogues. Already at the start our customers get the best deal, which in the future will pay back their investments faster than competitors.

Millennium Engineering is one of the first companies who have launched the development of the spiral conveyors with an external drive. We are pleased to share with you all the advantages of last generation spiral conveyor DLS-EVO.