ZenitXtreme – a new dimension in lift doors

They have been available since the beginning of the year: doors in extra-large dimensions for heavy duty industrial lifts are now available from the lift door specialist Meiller Aufzugtüren GmbH in Munich: ZenitXtreme.

It is not just the door clearance widths (from 2400 to 8000 mm - 8 m! - in the six-section, centrally-opening version and from 1600 to 5300 mm in the four-section, centrally-opening version) that are extreme. In each case, the maximum door height can be up to 5000 mm.

The sturdy door concept has been specially designed for rough industrial operations. The aim of the sophisticated technology is to guarantee high availability of the lift, according to the company.

The transom, upper frame, sill bracket, sill and apron are centrally divided in all door widths, making the individual assemblies easier to handle and mount. In general, the whole idea behind the new heavy duty door is installation-friendliness: the transom is attached to the wall by attachment brackets on top of the transom and aligned vertically using a jig. At the bottom, it is adjusted vertically by ejector screws.

The heavy load steel sill (max. wheel load 5.0 tons) is also always divided in two. The guide grooves have only been lasered to the extent needed for the travel path of the door leaves.

Individually exchangeable profiles, sills and frames

A ram profile is mounted to protect the door leaves and side frames; when opened, the door leaves are protected 50 mm behind this profile. If damaged, the ram profiles, sills and upper and lower frames can be individually replaced.

The rollers and counter-pressure rollers (Ø each 120 mm) are turned out of a cast polyamide semi-finished material and pressed with an encapsulated ball bearing. The roller contour is optimally adjusted to the runner rail.

All sheet metal parts are made as standard out of Zn-Mg-coated or hot galvanised sheet metal. The frames and sill with substructure can also be made completely out of stainless steel. The door leaves are also available with stainless steel cladding but can likewise be made out of stainless steel.

Different door heights possible

The landing and car door are driven separately by the Meiller door drive system MiDrive. Optical coupling takes care of synchronous running of both doors instead of a mechanical catch combined with hook bolts. The drive, telescoping and deflection occur exclusively via chain drive instead of with ropes.

Since ZenitXtreme operates without skate and hook bolt, different door heights in a lift are no problem; ramp travel is also conceivable. Extremely small sill gaps can also be realised.

Thanks to its drive system, the landing door of the ZenitXtreme has a servo-supported emergency rescue system. As soon as the door drive system detects an emergency rescue, it opens the door 50 mm and gives the staff several seconds time to go to the centre and open the door.

When the door drive detects a force acting on the door leaf, the drive supports the opening electrically, similarly to servo-steering in a car. In this way, even heavy doors can be moved without much force. By contrast, if nothing happens within a few seconds, the door closes and locks again automatically.

Safety for service personnel

Value was also attached to great safety for service personnel in developing the ZenitXtreme: in the case of door leaf weights of 1600 kg and more, there is a great risk that a conventional, correspondingly great closing weight would close the landing door in an uncontrolled manner and injure people in the door area.

Consequently, the drive system has an electric closing device, which closes and locks the landing door in a controlled manner at nudge speed. The kinetic speed is simultaneously limited to 4J, greatly reducing the risk of injury.

ZenitXtreme is available in EN 81-20 and EN 81-50 versions with an additional type approval test. A fire-tested version according to EN 81-58 for defined dimension spectrums will supplement the product range in the second half of 2019.

www.meiller-aufzugtueren.de