PSK sliding door locking systems – breakage due to overload and correct replacement
In this blog, we explain where this breakage occurs, why replacement must always be done per four corners, and how to correctly identify the right PSK locking system based on the code on the upper corners.
Breakage due to overload in the PSK locking system
A PSK locking system consists of rods and four corner transmissions. In each corner, there is an aluminum block with gearing that converts the movement of the handle into locking force. This also applies to PSK systems from Gretch Unitas. Aluminum is deliberately the weaker material here to prevent greater damage to the fittings.
When a PSK sliding door does not run smoothly, hangs crookedly, or is operated with force structurally, too much load is placed on this aluminum gearing. The result is that the block breaks off. In most cases, the damage is visible in one corner, but the load has always affected the entire locking system.
Why PSK corners are always replaced in sets of 4
In case of a defective PSK locking system, the corners must always be completely replaced. This is technically necessary because all corners have experienced the same load and the other corners are already internally weakened.
In addition, PSK corners are only supplied and packaged in sets of four pieces. Individual corners are not available and are not intended for partial replacement. This also applies to PSK corners from Gretch Unitas. Replacing only one corner almost always leads to repeated malfunctions and consequential damage to the locking system.
Determine closing direction before identification
Before a PSK locking system is ordered or replaced, the closing direction must first be determined. This is always done by looking from the inside.
If the handle is on the left, the door is left-closing. If the handle is on the right, the door is right-closing. This step is essential and is often done incorrectly in practice by looking from the outside, resulting in incorrectly ordered parts.
Step 2 – check the code on the upper corners
The identification code of a PSK locking system is only on the upper corners, so upper-left and upper-right. There is no code on the lower corners. An example of such a code is:
LS 38742 13
Where:
– LS indicates the closing direction, in this case left-closing
– 38742 the product or system number of the PSK locking system
– 13 the spindle size is
The spindle size is a crucial technical specification. In PSK locking systems, this size usually appears as 9 or 13. The spindle size is always the last number in the code and must match exactly. Even a small deviation causes the locking system not to fit correctly or not to function properly.
Therefore, always carefully check the code on both upper corners before ordering parts.
Extensive explanation in video
For a complete visual explanation on dismantling and replacing PSK corners, an extensive instructional video is available on YouTube. This video explains step by step how PSK corners, including those from Gretch Unitas, are replaced and how the locking system is technically constructed.
The video can be viewed via:
This video is a valuable addition to the information in this blog and helps prevent installation errors.
Specialist advice and delivery in Europe
Technical knowledge is essential for the correct replacement of PSK locking systems. Van Doorn Openingstechnieken is a specialized dealer of PSK locking systems and parts, including systems from Gretch Unitas, and supplies these to installers and companies throughout Europe. By correctly identifying closing direction, spindle size, and system type, ordering incorrect sets is prevented.
Correct replacement prevents recurrence of damage
A sustainable repair of a PSK locking system always consists of a correct closing direction, an exactly fitting spindle size, a complete set of four corners, and a proper readjustment of the door after installation. Only in this way is the original function restored and new overload prevented.