GN 1420

Telescopic slides

Telescopic slides GN 1420 are installed vertically and in pairs. The stroke reaches ≈ 100 % of the nominal length l₁ (full extension). The rubber stops of type E dampen the impact of the slide in the two end positions and takes on the locking function of the back stop position. This feature is noticeable through a slight resistance on opening and closing. If larger static or dynamic loads occur in the direction of extension, they should be absorbed by external stop elements.

The telescopic slides are delivered in pairs. They can be installed on the extension on either the left or right side due to the mechanics. All mounting holes are easy to reach through auxiliary holes. Only the mounting holes are shown, but other production-related holes may be present.

• other lengths and hole spacing

• other attachment options

• with latches, partially with detach function (back, front, or back-front)

• with locking device (front or back-front)

• other surfaces

• with support bracket

Mounting holes - outer slide

 

Mounting holes - inner slide

 

Fastening screws

General information

Telescopic slides offer smooth running, wear-free, and quiet linear motion. They are used in a very wide range of applications. The spectrum ranges from the most simple extensions and drawers to high-quality variants that are used in the industrial environment on machines, production systems, and equipment. The telescopic slides have a multitude of positive features and are still very interesting from an economic standpoint. Here are a few examples of use: sliding doors, protective hoods, keyboards and PC pullouts, vehicle equipment, storage shelves, battery boxes etc.

Telescopic slides can come with a number of component options. Some are available for one of the two stop positions and in combination, and they are defined by the type in the article number.

Structure

Telescopic slides consist of an outer and inner slide as well as additionally of one or two middle slides depending on design and/or required extension lengths. The slides are interconnected through appropriately shaped geometry and move by means of ball bearings. A ball cage keeps the bearings spaced and in position.

The slides are usually mounted through countersunk holes or through-holes. Other options, such as threaded bolts or support brackets, are available as an alternative.

In regard to the length of the extension, telescopic slides can be divided into three categories: partial extension, full extension, and over extension. The categories are defined by the achievable stroke l₂, which is listed in relation to the nominal length l₁.

Type of extension	Extension diagram
Partial extension: l1 = 100 % -> l2 = min. 75 %
Full extension: l1 = 100 % -> l2 = min. 100 %
Over extension: l1 = 100 % -> l2 = min. 150 %

All slides have internally constructed stops in the front and back end position. The stops prevent the slides from extending unintentionally. Depending on the available installation space and required stability, the stops are designed accordingly in a metallic form or with additional plastic or elastomer parts as a rubber stop to prevent the slides from hitting the end positions with too much force.

Also the telescopic slides can come with a variety of accessory functions. Examples include locking devices, latches, detach functions, and self-retracting mechanisms, some of which are dampened. Some additional functions are available, depending on slide variant, for the back or front stop position and in combination. Furthermore, customer-specific modifications regarding the fastening of the slides can be made.

Telescopic slides with full extension, back stop position

 

Telescopic slides with full extension, front stop position

 

General installation information

• Telescopic slides are generally installed in pairs so that the mounting surfaces of the housing and extension side are level, parallel, and perpendicular and have to be aligned with one another correctly in regard to position. Furthermore attention should be given to adequate stability of the receiving structure so as to keep geometric errors caused by elastic deformation as minimal as possible.

• Fastening holes should be applied in such a way that excludes twisting or warping of the slides during mounting. Also the slides need to be positioned in the direction of extraction in such a way that the extensions reach the end position at the same time on retraction and extraction. In this way, an equal amount of stress acts on the rubber stops and locking devices.

• The width of the respective slide installation spaces should be designed with a tolerance of +0.2 / +0.5 mm. The slides will then tension slightly in the direction of the middle of the extension. This promotes optimum performance and a long lifespan.

• Before mounting, the inner slides should be moved to the front and back stop position once to allow the ball cages to assume their intended position. Installation should also take place at room temperature.

• After mounting, check the telescopic slides and extensions for ease of movement. If something is wrong, such as sticking or warping, the cause has to be determined and eliminated through appropriate actions.

Mounting holes, fastening screws

In general use all holes intended for fastening when mounting telescopic slides. Doing so will ensure that the forces resulting from the maximum load capacity F_S (nominal load) can be transferred safely from the telescopic slides from and to the surrounding structure. Failure to use fastening screws reduces the specified load capacity accordingly.

The outer and inner slides have other openings and auxiliary holes in addition to the holes intended for mounting. The catalog drawings and the CAD data available for download do not show these holes to exclude confusion and design faults. These holes are needed, among other things, for the fastening of type-dependent component features, such as the self-retracting mechanisms.

Some slide variants have fastening options for screws of various sizes. In this case, all positions of a size or type should be used. Auxiliary holes, which ensure that all mounting holes can be reached, are found accordingly in the CAD data, but are not pictured in the catalog drawings.

The type and specification of suitable screws can be found on the respective catalog pages. It is generally recommended to use screws of tensile strength class 8.8 under consideration of the specified tightening torque.

Installation position

Telescopic slides are preferably installed arranged vertically and in pairs in a horizontal position. This ensures that the highest possible stability and torsional stiffness is reached in the smallest installation spaces and allows for absorption of the maximum load (nominal load). The performance features are optimum in this installation position, and wear is reduced to a minimum.

The horizontal or lying installation of the slide is likewise possible with certain restrictions. The maximum load in this case is only about 20 % to 25 % of the specified nominal load. The less favorable slide profile results, therefore, in considerably higher bending in the extended state. As a result, the ball cages may leave streaks on the heads of the fastening screws. In case of doubt, check the function under load in a test set-up.

Installing slides in a perpendicular position to the direction of extraction is not recommended because increased cage slip occurs in this case. This means that the upper and lower end position of the slide can be reached in some circumstances only with an increased amount of force after a few cycles since the force of gravity causes the ball cage to become dislocated from its correct position.

The following examples show possible installation positions of telescopic slides that are considered favorable or acceptable and some that are regarded as unfavorable and should, therefore, be avoided.

favorable	vertically, both sides, favorable
acceptable	vertically shifted, on both sides, acceptable	vertically inclined, on both sides, acceptable
unfavorable	vertically, on one side, unfavorable	horizontally, on both sides, unfavorable

Load capacity

The maximum load capacity of telescopic slides depends on the slide profile, the nominal length l₁, and the resulting stroke l₂. Furthermore, the extension width, the slide materials used, and the parts of the component options, such as the dampened self-retracting mechanism, have a considerable influence.

The information on the maximum load capacity of the telescopic slides was determined in fatigue tests under the following

• Slide arrangement vertical in pairs

• Observance of all mounting information

• Equal distribution of the load F_S throughout the extension finish

• Standard slide spacing of 450 mm

• 10,000 or 100,000 test cycles (one extraction and retraction = one cycle)

• Gradual increasing of load

 

Bending

Telescopic slides demonstrate elastic bending under load in the extended state. The bending is most noticeable at the far end of the inner slide. The general rule is that the extent of deformation may not be higher than 4.25 % of the stroke path. All slides are within this value on maximum load.

 

Tolerances

Travel speed

Slide materials, surfaces and corrosion protection

The telescopic slides made by Elesa+Ganter are manufactured out of high-quality steel or stainless steel bands.

The stainless steel telescopic slides are generally delivered with mill-finish surfaces.

The steel telescopic slides are partly made out of a pre-zinc plated steel band and are subsequently batch zinc plated and blue passivated with 5 to 7 μm. Corrosion resistance in the salt spray test for at least 72 hours against white rust is ensured in this way.

• Galvanically batch zinc plated 5 to 7 μm, black passivated, corrosion resistance in salt spray test for at least 120 hours against white rust

• Galvanically batch zinc plated 5 to 7 μm, passivated, electrolytically coated with T2 top coat / sealer 8 to 12 μm, corrosion resistance in the salt spray test for at least 96 hours against white rust / 500 hours against red rust

Lubrication and maintenance

Telescopic slides are permanently lubricated with high-quality, mineral-oil-based and lead-free bearing lubricants.

For stainless steel telescopic slides, special FDA-compliant lubricants are used that are tasteless and odorless. The lubricants comply with lubricant class H1, which allows them to be used in areas where it is technically infeasible to prevent occasional contact with food. Generally direct contact can be prevented by taking appropriate actions, such as optimum placement of slides or the use of covers.

Re-lubrication is generally not necessary under normal conditions of use since the ball cages and bearings “push out” small amounts of obtained dirt from the slides when the slides move. In applications where there is heavy contamination, the slides should be cleaned from time to time with a clean cloth and then re-lubricated. Acceptable lubricants for the steel variants are, for example, Shell Alvania EP 1 and Klüberplex BE 31-222.

Cage slip

Temperature of use

Information

Telescopic slides can be delivered with a number of component options. Some are available for one of the two stop positions and in combination, and they are defined by the „type“ in the article number.

The following overview shows examples of possible characteristics of the various types and component features. The components used and the employed mechanisms are adapted to match the available installation space, cross section, and structure of the selected slides and have accordingly different designs depending on slide variant. Functionality is comparable, however, and sometimes even identical.

Rubber stops

The rubber stops used in almost all slide variants dampen the impact of the slide in the respective end position. This feature minimizes noise development and increases the lifespan. Attached to the slides in a partially concealed, partially visible manner, the stops meet each of the requirements in regard to shape, material, and hardness.

If larger static or dynamic loads occur in the direction of extension, they should be absorbed by external stop elements.

 

Locking devices

The locking function is noticeable by a slight resistance of the slides in the end positions, which has to be overcome on opening and closing. The locking device in the back stop position is usually integrated into the rubber stop function, making additional components unnecessary.

The locking device is frictionally engaged and, therefore, does not act as a positive locking latch.

 

Latches

Unlike locking devices, a latch secures the slides in the stop positions in a frictionally engaged way. Telescopic slides with latches are used when the slides need to be protected against independent extension or retraction, for example, due to a tilted position.

A mechanism found within the inner slide latches automatically spring-loaded by moving over a ramp on reaching the respective stop position. Pressing the release lever releases the latch, allowing the slide to move again.

If larger loads occur in the direction of extension in the latched position, they should be absorbed by external latch elements.

 

Self-retracting mechanism

Telescopic slides can have an integrated self-retracting mechanism, which improves considerably the ease of use when closing the extensions.

In the version shown in the example, the slides are retracted and held in the back end position automatically by means of a retraction mechanism on the last 22 mm of stroke with a force of approximately 30 newtons for each slide pair. This force has to be overcome accordingly on opening the extension.

This variant is also designed in such a way that mechanism uncouples and will not be damaged when the extension is opened or closed in a jerky manner or too quickly. On the following stroke, the self-retracting mechanism clicks back into place automatically, ensuring that the function remains intact.

 

 

Self-retracting mechanism, dampened

Dampened self-retracting mechanisms are also called “soft-close” and are divided into two main functions. They offer the best possible ease of use on closing the extension.

In the example shown, the self-retracting mechanism takes over the automatic retraction of the slides on the last 40 mm of stroke in the back stop position, where the slides are then held in place. The retraction force is about 35 newtons per slide pair. Also the dampening mechanism slows down to a considerably reduced speed the closing movement on the said stroke, while achieving a extremely gentle and smooth closing movement. This retraction force has to be overcome accordingly on opening the extension.

When dampened self-retracting mechanisms are used, the specified load values and stroke speeds may not be exceeded on reaching the retraction mechanism.

 

 

Detach function

Telescopic slides with a detach function can be completely separated from one another in the area of the middle and inner slide. This feature not only facilitates mounting. It also allows the extension to be quickly removed, for example, when maintenance work is performed on the components located behind.

In the example shown, the telescopic slide can be quickly and easily detached in the extracted position through activation of a flat spring, allowing the inner slide to be removed from the front.

For reattaching the slides, the ball cages need to be moved basically to the front end position. Then the inner slide is inserted to the back end stop where it locks back into place automatically.

The protected arrangement of the various release mechanisms prevents accidental detachment of the slide.

 

 

Support and mounting brackets

Support brackets on the inner slide are available on request for some slide variants, even in small quantities. The support bracket is used for simple fastening, for example, of a drawer, if side mounting is not possible. Fastening occurs by means of through-holes that are arranged at a right angle in the bracket.

The fastening screws secure only the position of the drawer in this case. Additional reinforcement of the slides themselves, as with side mounting, is not possible. The drawers should therefore be designed as rigidly as possible so that the perpendicular load does not introduce any unnecessary tension through the support bracket into the slides.

 

„Push to Open“ - mechanism

Telescopic slides can be fitted with a “push to open” or “touch to open” mechanism. In addition to ease of opening, the system allows you to have drawers without a front handle. This makes it easy to achieve a sleek, high-end appearance.

The system is typically actuated by pressing your hand on the front of the slide-out shelf or drawer. In the example shown here, the required force to activate the opening mechanism is about 40 N per rail pair. The inner rail extends 5 mm in its home position and can be pressed in by about 8 mm in the closing direction. This should be taken into account in the design in order to prevent collisions. The pressure or release point is reached at about 3 mm, which causes the drawer to slide out smoothly to about 40 mm in the opening direction after being released.

When using telescopic slides with “push to open” actuation, the load values and travel speeds upon reaching the retraction mechanism as specified in the respective standard sheet may not be exceeded.

 

 

Information

Countersunk holes	Other fastening holes	Press nuts
Threaded studs / bolts	Mounting studs / bolts	Fastening clips
Mounting plates, spot-welded	Spacers, spot-welded	Support brackets, spot-welded