It is necessary to install a barrier if a scissor lift table is not safe due to the installation situation and people can enter the hazard zone underneath the platform. The logical question now is which barrier should it be? In this article we would like to help you to answer this question.
We offer four different types of safety measures for our lift table :
- The corrugated wire-mesh screen
- The PVC roller screen
- The bellows
- The sheet metal apron
The corrugated wire-mesh screen or chain curtain is the simplest type of barrier. A curtain made of interwoven metal elements is attached to the underside of the platform. Except for the top brackets to hold the screen or curtain, no special fixtures need to be attached to the lift table. This makes this variant the least expensive solution to safeguard the area under the scissor lift.
A big advantage of the corrugated wire-mesh screen compared to a PVC roller screen or bellows is that it offers only a very small windage surface due to the many small openings and its own weight. This eliminates the risk of the corrugated wire-mesh screen being pushed into the moving parts of the lift table. For this reason, we almost always recommend the use of a corrugated wire-mesh screen for an outdoor lift table.
If you want to move the lift platform more often, we would however advise against using a corrugated wire-mesh screen. Without an appropriate tray, the chain curtain rests on the floor and will be a hindrance during transport. Instead of making a holding tray, we would rather advise using a PVC roller screen.
The PVC roller screen is a tarpaulin glued onto a spring shaft. The spring shaft is pre-tensioned when the scissor lift is raised, so that the tarpaulin is rewound when the lift is lowered again. In addition to the spring shaft bracket, an appropriate counter bearing on the base frame of the lift table is also required. The structure that the PVC roller screen is already an indication that it is more expensive than a corrugated wire-mesh screen. Pricewise it lies between the corrugated wire-mesh screen and the bellows.
Compared to the corrugated wire-mesh screen, the PVC roller screen has two advantages:
- Fixed connection to the base frame
The PVC roller screen has a dedicated attachment on the base frame, making this structure also suitable for mobile lift tables.
- Easier access for maintenance
A PVC roller screen provides faster and easier access if you need to enter the hazard zone for maintenance or repair work. All that needs to be done to gain access is to loosen the screws of the bottom attachment. The spring shaft then rolls itself up automatically.
The bellows or box-type bellows is probably one of the best-known solutions as a barrier. Its popularity is mainly due to the wide range of possible applications. For example, bellows come in all possible dimensions and geometries for a wide variety of machines. Its design is similar to that of an accordion. It consists of many small folded plastic sections glued together. When retracted, these folded sections lie close together, and are pulled apart when extended. The bellows is attached to the platform of the lift table with special clamps. A cradle must also be created on the base frame.
One of the great advantages of bellows is that the hazard area underneath the lift table is completely protected. Whereas the corners of the platform with a corrugated wire-mesh screen or a PVC roller screen are still freely accessible, this is not the case with a bellows.
The sheet metal apron is a very special barrier design. In most cases, this type of barrier is only selected if the effective stroke of the lift table is very small. This makes the installation of a sheet metal apron very cheap and even beats the price of a corrugated wire-mesh screen.
The protective effect is based on the fact that the sheet metal apron is longer than the effective stroke of the scissor lift. If the lift table is installed in a pit, the bottom edge of the sheet metal apron is still below floor level even when the lift table is raised. This means that there is no danger that a person can enter the hazard area underneath the lift platform. Another advantage of this solution is that the foot protection safety edge can be dispensed with.
As the effective stroke increases in height, the cost ratio of the sheet metal apron becomes unfavourable compared to the other designs. At some point, it is unfortunately no longer possible to use a one-piece apron, which means a telescopic apron becomes necessary. Although the telescopic apron has the advantage that it is not susceptible to wind and offers complete protection, the design and manufacture of the apron is costly. It is therefore rare to find a sheet metal apron as a barrier in scissor lifts with an effective stroke that exceeds the overall height.
We often receive enquiries whether the use of a barrier makes the installation of the foot protection safety edge or even a landing enclosure expendable. Except for the sheet metal apron, none of the types of barriers presented above allows dispensing with other protective equipment. The reason for this is that the barriers presented above do not completely prevent access to the hazard zone. For this reason, the hazard zone must be specially protected if necessary. However, there is more than one way to provide this protection. Talk to us and we will help you with your special application.