Transport systems Electric monorail conveyor systems

Editor: Theresa Knell

Electric monorail conveyor systems (EMS) have been established internal transport systems for decades. They can be used across industries. This article describes the basic technology and structure of electric monorail systems. Some examples illustrate the possible applications of EMSs. They are suitable for a wide range of intralogistics processes and for transporting a wide variety of goods and for applications in production, manufacturing and assembly.

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Electric monorail conveyors are frequently used in automobile production, such as shown here for car body transport, or in final assembly.
Electric monorail conveyors are frequently used in automobile production, such as shown here for car body transport, or in final assembly.
(Source: Rofa)

An electric monorail conveyor (EMS) is an ground-free, rail-bound conveyor with individually driven trolleys that move independently on a rail system. With the help of switches, junctions can be realized on the track. The rails are either attached to the hall ceiling or, if it is too high, to a suspended or elevated steel structure. The trolleys are usually supplied with power and control signals via conductor lines fitted on the mounting rail.

Various advantages of electric monorail conveyors

  • fast, gentle, silent and energy-efficient transport;
  • transport across several levels;
  • ground clearance and flexibility;
  • extremely high availability;
  • low investment and performance increase.

The use of an electric monorail conveyor is ideal when long distances or different buildings have to be logistically linked or high throughputs have to be handled. In contrast to stationary conveyor technology, it is "much more efficient and faster", reports Eisenmann, one of the leading manufacturers. The individually driven and controllable trolleys enable the goods to be transported quickly, fully automatically, efficiently and safely to their destination in the shortest possible time.

Transport of pallets, steel box pallets and individual load carriers

An EMS offers high flexibility. The basic structure of the trolley is always the same, but the suspension can be individually designed according to the respective requirements. Pallets and steel box pallets can be transported just as easily as individual load carriers.

High plant availability

Today many industries, especially logistics, require almost 100% plant availability, which is crucial when deciding on a particular technology. Electric monorail conveyors meet this need, because if a trolley breaks down, it can be pushed from the transport line into the maintenance bay without great effort. The material flow continues uninterrupted.

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Continuous transport across multiple levels

An electric monorail offers continuous transport across several levels. If it is necessary to connect different levels in plant or logistics facilities, the use of an inclining EMS is the obvious choice. The change to the other level takes place in in one run, which has a positive effect on throughput times. Compared to systems with lifting stations, investment, operating and maintenance costs are reduced.

Different rail systems for a wide range of loads

The wide range of loads transported by EMSs, requires different rail systems. Eisenmann's graded rail system, for example, covers different weight ranges: "Depending on the payload, the appropriate support rail with the required bending and torsional strength is used; our 180 mm hollow-chamber section, for example, is very popular in intralogistics."

The track system of the electric monorail system does not require any stationary sensors or conductor rails for control tasks along the route. Adjustments to the routing or subsequent plant extensions can be implemented very easily and quickly.

Extensive and cross-industry application spectrum of the EMS

Electric Monorail Systems comprise applications in intralogistics for the fast and flexible transport of all types of load carriers, for assembly and production tasks, for example in the automotive sector and in flexible production lines. In addition, they are generally used to distribute, sort, store, buffer and provide goods and commodities, as well as in flight catering and order picking solutions.

For example, Eisenmann realizes both goods-to-man and man-to-goods picking by linking manual picking processes with electric monorail systems, with particularly high throughput rates being achieved in each case.

"The advantages are in the minimization of transport and distribution times, so that a dynamically scalable picking system is created."

Transport tasks as well as supply and disposal of the order picking system

Eisenmann equipped Ikea's logistics center in Dortmund with a 3500 m long electric monorail system. Besides transporting goods, the system is used for supply and disposal in goods-to-man order picking. The EMS is guided to 384 picking stations in 48 bays, where picking takes place directly on automatically provided shipment pallets. The order pickers receive their orders on the EMS trolley according to the pick-by-light principle and also confirm the execution here.

Louis Schierholz GmbH, for example, uses electric monorail overhead conveyors at airports in Frankfurt, Dubai and Korea for high-frequency transport of various airline carts for in-flight catering, duty-free and service articles. One of the facilities comprises 200 vehicles of the System 636 vehicles operating on a 2550 m line. The plant is equipped with 109 switches and 27 lifting stations and has a capacity of 360 trolleys per hour.

Different manufacturers of electric monorail conveyors

Eisenmann, for example, offers various trolleys for its electric monorail systems:

  • The standard 2-wheel trolley transports pallets efficiently and reliably.
  • The 3-wheel trolley is used for higher payloads.
  • The 4-wheel trolley "Twin Shuttle" maximizes throughput with minimum space requirements by accommodating two pallets each and offers new possibilities in layout planning.

The trolleys guarantee transport speeds of up to 180 m/min on the straight and up to 60 m/min in curved rails.

Rofa Industrial Automation offers three different EMS systems:

  • The KB 125 system is designed for payloads of up to 300 kg and moves at speeds of up to 120 m/min.
  • The KB 180 electric monorail conveyor is suitable for 1500 kg payload and can move up to 150 m/min.
  • The EHB KB 240c an handle loads of up to 10,000 kg and can move at speeds of up to 60 m/min.

The systems of the SFI-Group are designed for loads from 50 kg to more than 8000 kg.

Suitable for inclines of up to 90°

Schierholz's two standard systems for payloads of up to 1500 kg (System 636) and 3000 kg (System 645) move at speeds of up to 90 and 120 m/min respectively. The System 636 can handle inclines of up to 90°.

SEH Engineering offers its standard EMS designed for a load-bearing range of up to 1500 kg with a 180 mm section rail which complies with the guidelines for a compatible EMS rail according to VDI guideline 3643. The electric monorail conveyor is available in a mono trolley version, which is suitable for a climbing section of up to 90°, while the multiple trolley can handle climbing sections of up to 45°.

Additional Information
Power and Free

A frequently used overhead conveyor system is Power and Free, usually abbreviated P&F. The example of Schierholz's P&F system describes how piece goods conveyors transport a payload on a running gear mounted on a rail by means of a closed, circulating pull chain. The running gear and pull chain are positively connected to each other via a jack system.

Hargassner uses an extensive power-and-free system with a chain length of 1400 m and eight chain cycles for surface coating purposes.
Hargassner uses an extensive power-and-free system with a chain length of 1400 m and eight chain cycles for surface coating purposes.
( Source: Schierholz )

With switches and chain changes, the running gear can change the chain cycles and transport streams can be separated or combined. Stopper units can be used to separate the running gears from the conveyor chain and create storage areas, loading and unloading points or handling stations. Schierholz reports that this solution is ideal for all areas of surface technology and the stainless-steel version is suitable for the oven area in the food industry. The system can handle inclines of up to 90°.

This article was first published by MM Logistik.

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