Door latch device. How to install a latch with an additional locking mechanism: procedure

The finishing works on apartment renovation include the installation of interior doors, often with a magnetic mechanism. Their set includes a door leaf and racks, from which the frame is assembled. Doors mounted between rooms do not include fittings in their set, so they must be purchased separately. The magnetic latch for interior doors is one such element.

Interior door latch device

It is a simple product with a lock, which is built into the handle or installed separately. The device is necessary for simpler and more convenient opening / closing of the leaves, while they are characterized by an attractive appearance. The mechanism ensures the tightness of the door leaf closing. In this way, the room is kept warm and the noise does not propagate to the rest of the room.

The likelihood of injury is also minimal. For example, due to a draft, a door that is not equipped with a latch can slam shut, hitting the owner. There are several types, the differences between which are in the design and the working mechanism.

Types of door latches for interior doors

To meet the needs of the buyer, manufacturers offer several latch options. Below are the most popular latches for interior doors.

Latch with handle

Their other name is push. When you press the handle, the latch moves, which reliably holds the interior door in the closed position. Due to its wide distribution, such a model can be found both on the interior and on the entrance canvases. Often this type is supplemented with a locking mechanism.

There are two subspecies of this design:

• with a base-fifth (point-mounted);
• with an elongated bar that allows you to change the position of the keyhole.

Magnetic interior door latch

Magnetic device with almost silent operation - when closing the door leaf, you will not hear a click, as happens with a latch mechanism. The main difference is simple installation. You do not need to carefully adjust the interior door to the box, since a magnetic product can work perfectly, even if the canvas is slightly skewed.

As for the design, it is quite simple, because it consists of only two elements: a metal plate and a magnetic block. There are also more complex magnetic latch mechanisms. For example, a locking device has a moving magnet in its design.

Latch for interior doors with a latch

Fale latches, unlike magnetic ones, are equipped with a mechanical tongue. The task of the beveled tongue is to prevent the door from opening inadvertently. To do this, it must fall into a groove of a special shape. If everything is correct, you will hear a click. To open such interior doors, it is enough to turn the handle: the mechanism is activated, compresses the spring and releases the tongue.

This design is widespread and can be found on most lever and thumb levers. Rotary products are made in the form of a ball or oval (sometimes a cylinder), and they are called knob handles.

The latch itself can be push-button or lever. Its task is to limit functionality on one side of the canvas. Such locks are most often installed on the doors of a bedroom, study or bathroom.

Advantages of latch latches:

• simplicity;
• easy insert of a latch into the interior door with your own hands;
• range.

But, there are also disadvantages. For example, the vulnerability of an interior door latch with a latch is the latching mechanism itself, which has low resistance to damage.

Silent latch for interior doors

Silent latches make consumer life a little more comfortable, especially with magnetic base options.

• devices with tongue and plastic inner mechanism;
• magnetic latches.

Both options are progressive when compared to traditional movements, which is why they are bought more and more often. Magnetic types are now actively manufactured by the Chinese market, but products with plastic are less common, due to their price.

Dimensions of interior door latch

When choosing door hardware (especially magnetic), you should pay attention to its size. The main parameters are:

• length is of no small importance, especially if the canvas is decorated with glass or other decorative elements;
• width - should be less than the canvas itself;
• length and width of the fixing strip (located at the end of the door).

The dimensions of the interior door latch are individual for each product.

How to choose the right interior door latch

There are several points, starting from which you can choose a suitable mechanism:

• the latch must be of high quality and reliable (no chips, scratches, with a durable color);
• if the choice falls on magnetic fittings, then you need to check the magnet itself;
• it is worth evaluating how comfortable it is to hold on to the door handle, since you will have to interact with it every day;
• door hardware must match the interior and finish;

  Important! The handle is chosen in the same color as the hinges with a lock.

• the location of the rooms and their functional purpose are taken into account: for neighboring rooms, the same models are often chosen, but if the interior doors are located at a distance from each other, then you can think over different options;
• the degree of load on the handle - if you install flimsy magnetic fittings on a powerful massive door, then it will quickly become unusable;
• coming up with original solutions, do not overdo it, a pretentious model will look ridiculous in an apartment with a conventional renovation, but a simple one with a magnetic element will suit any interior.

Handles are made from different materials; the consumer's choice often stops at the following options:

1. M etall. Such products are the most durable and wear-resistant. When applying different coatings, you can get a new solution in terms of color and texture. The most popular models are made of brass, they combine quality and price. The main disadvantages of metal products are that the surface always remains cold, and budget options quickly lose their attractiveness.
2. Wood. Best suited for similar materials (solid or veneered). For their manufacture, wood of different species is used, including valuable. Ornamental inserts, inlays or carvings can serve as decoration. This solution is not suitable for kitchens and bathrooms due to its low resistance to high humidity.
3. Glass. These products will be a wonderful decoration for any interior. But, they are fragile and expensive.
4. Plastic. Such accessories are the cheapest and most short-lived. They are installed in rooms such as utility rooms. Among the shortcomings: poor quality, unpresentable appearance.

How to insert a latch into an interior door

The installation procedure is as follows:

1. To make it easier to work, the canvas is removed from the hinges and fixed on a stand.
2. Next, markings are applied to the canvas. The optimal height from the bottom of the door is 95 - 100 cm. At the same stage, the locations of the handle and latch are marked. To facilitate the work, a template is used (often it comes with a latch).
3. For the latch, a hole is drilled from the end, and for the handle - from the front. Experts advise starting from the front side.
   
   
4. On the sides of the hole prepared for the latch (magnetic or simple) there will be a niche where the mounting plate is inserted.
   
   
5. Install the lock and fix it using the fastening bolts included in the kit.
6. Attach the handle of the fixing element. The correct installation diagram is included with each device. As a rule, first the handle is disassembled, after which its individual elements are attached.
   
   
7. The final stage is the installation of the striker, where the fixing tongue will go. To do this, a niche is made opposite the castle and a bar is installed there.
   
   

Important! If the latch is installed correctly, then it will not touch the elements or make squeaking sounds during operation.

You need to know how to properly operate a magnetic lock - only in this case it will serve for a long time and reliably. Here are some simple rules:

• the magnetic element and the striker must be cleaned of adhering debris and metal dust;
• it is best to follow the instructions during installation to ensure the manufacturer's stated downforce. The recommended size of the gap is important - if you "go" from the parameters even by a couple of millimeters, the holding force will decrease, this also applies to the magnetic latch;
• to prevent oxidation of the magnetic mechanism, all elements are wiped from moisture;
• check the fastenings of the lock, magnetic block and counterpart, if necessary, tighten the screws.

A correctly installed magnetic lock can last for many years.

Conclusion

The magnetic latch for interior doors is a reliable product with a simple design, designed for a considerable service life. They are also popular due to their simple installation, which even a beginner can do.

In the living area, latches are installed on the interior doors, allowing them to be fixed in the closed position. Interior latch can be of various types, which makes it difficult for an ordinary consumer to choose. How to choose a device yourself and install it without the help of specialists, you can learn from this article.

Varieties of door latches

The main criterion for choosing latches for interior doors is the type of device. Latches are classified according to the following parameters:

• type of locking mechanism;
• installation method;
• presence / absence of additional functions.

Latch types

Currently produced:

• mechanical latches;
• magnetic latches.

A mechanical latch is a device that operates using a spring mechanism.

Door mechanical latch can be:

1. fallopian. The latch handle is a device equipped with a locking tongue with an oblique cut. When applied to the tongue, it moves away, and the spring returns it to its original state. A special strip is installed on the door frame to fix the locking tab. Depending on the method of action on the locking mechanism, there are:
   • rotary knobs, that is, the tongue is activated when the handle is rotated;

• push handles, that is, the locking element responds to pressing the handle of the device;

1. roller. The locking mechanism of the device is a roller, which, when the door is closed, falls into a special groove.

Roller latches are predominantly installed on the door of a children's room, since they are easy to open and close and cannot be fixed.

The most famous manufacturers of mechanical latches are:

• Apecs;
• A magnetic latch is a device based on a magnet that attracts a metal bar.

Such a device is different:

• noiselessness and smooth operation. When the door is closed, no click is heard from the locking element getting into the groove;
• durability. The latch can be used for a long time without additional maintenance, as it consists of the simplest elements.

The most popular manufacturer of magnetic latches is Palladium. What device to install on the interior door? It's up to each user to decide.

Classification of latches by mounting method

The latch can be installed:

• inside the door leaf. The mortise latch has a more pleasant appearance, since the main mechanism is located inside the door. However, the installation of such a device is more complicated;

• on the surface of the door leaf. The overhead latch device is located on the door, which somewhat spoils the design of the room, but installing the latch is quite simple.

Mortise latches of various types are more popular among consumers.

Additional abilities

The standard latch can be supplemented with:

• retainer. A latch with a latch is mainly installed on the door of a bathroom or toilet room, since it allows not only to keep the door in a closed position, but also to protect the room from penetration;

• lock. Key operated latches designed for low-security office environments.

Latch installation process

How to install a latch on an interior door yourself? Overhead latches do not cause problems during installation, as they are attached to the door with fixing bolts. The following tools are required to install the mortise latch:

• marker and tape measure for marking;
• drill, complemented by a set of drills and a wood crown;
• chisel;
• a hammer;
• screwdriver (set of screwdrivers).

The installation of the interior latch is done in the following way:

1. at the first stage, it is necessary to mark the door leaf for the installation of the device. When marking, the following are noted:
   • installation area of \u200b\u200bthe locking mechanism;
   • door handle mounting area;
   • the area of \u200b\u200bthe bar;
   • device attachment points;

The markings can be applied more precisely using a template.

1. at the second stage, holes are drilled for mounting the device elements. The hole for the locking mechanism is drilled with a feather drill of the appropriate diameter, and the hole for the handle is drilled with a crown;

1. a niche is formed at the end of the door for mounting the latch strip;

Anyone has to periodically face the need to do something for the first time in life. If you decide to install latch handles in the interior doors of your apartment, but have never done anything like this before, at first glance, you may get the feeling that it is not easy to do this with your own hands, and it is better to seek the help of a specialist. However, in fact, the technology of installing a handle with a latch on an interior door is quite simple, the main thing is to follow the instructions. If you have all the necessary tools at home (a square, an awl, a pencil, a drill with a feather drill and a crown with a diameter of 50mm, a hammer, a chisel, a screwdriver or screwdriver, a marker), then the process of installing the door latch handle will take you no more than one and a half hours.

Variants of handles with latches can be conditionally divided into three types:
1) simple handles without a lock - used in rooms that do not need to be locked either from the inside or from the outside;
2) handles with a latch, that is, a mechanism that allows you to lock the door while inside the room;
3) handles-latches with a turnkey connector on the outside and a latch on the inside, that is, with the ability to lock the door both from the inside and from the outside.

By the type of mechanism, the latch handles are divided into lever handles and knob handles. The latch arms look like a lever in appearance and include a push mechanism that is activated when the lever is pressed (usually from top to bottom). The knob-handles have a round or spherical shape and a swivel mechanism that performs its functions when the handle is rotated.

As a rule, in stores and building supermarkets, door latch handles are sold complete with all the necessary parts, a special key, as well as installation instructions and a detailed marking scheme for the door leaf with all dimensions.

The very process of installing a latch handle on an interior door is almost the same for all handle options, regardless of the features of their device and the mechanisms used in its design. Let's consider the process of mounting the latch handle in more detail.

First of all, you need to perform the markup - using the template scheme provided in the kit, or on your own. Having determined the height of the door handle that is comfortable for yourself (usually it is 90-100 cm from the floor surface), it is necessary to make a corresponding note with a simple pencil on the door leaf. The center of the future hole for the handle should be at a distance of 60 mm from the edge of the door, this point should be marked. Then the markings should be transferred to the end of the door - usually a square is used for this, allowing you to draw a pencil line strictly perpendicular to the edge of the door. At the end of the door leaf strictly in the middle, it is necessary to mark the center of the drawn line with an awl. It is not necessary to make a mark on the other side of the door leaf also at a distance of 60 mm from the edge, but it is still recommended for the convenience of further work.

The next step is to make holes for the handle in the interior door leaf. In total, you should end up with three holes - one at the end of the door and two on the outside and inside, respectively. To make a hole in the end part, you will need a drill with a feather drill, using which you should drill a hole with a diameter of 23-24 mm in the end of the door leaf. Next, we move on to drilling the remaining two holes. To do this, you must install a crown with a diameter of 50 mm on the drill. It is important to take into account that in order to preserve the door leaf cover, it makes sense to drill a hole for the latch handle on each side separately, because if you drill one through hole using a drill only on one side, there is a risk of damage to the coating when the drill comes out to the opposite side of the door leaf. After completing this stage, you should have three neat holes in the interior door leaf.

Now we turn to the installation of the latch mechanism itself in the door. Having placed the mechanism in the hole on the end part of the door leaf, you should carefully trace the face plate at the end of the door along the contour using a simple pencil. Then we remove the mechanism and, using a hammer and a chisel, carefully make a groove on the end of the door along the outlined contour in accordance with the thickness of the face plate. As a result, the overlay should be located in the same plane with the end of the canvas, not protruding outward, but not "sinking" into the thickness of the door, that is, it should be installed flush. When this goal is achieved, all that remains is to mark by attaching a bar and drill holes in the end of the door for screws with which the cover will be attached to the canvas - the holes should be slightly smaller in diameter than the diameter of the screws - and screw the latch mechanism with the cover to the door using screwdriver or screwdriver.

Then it is necessary to install the actual handles in the door leaf. To do this, on one side, insert a cover plate with a square-shaped rod into the latch mechanism, making sure that the rod itself and screw sleeves enter the corresponding holes in the latch. After that, you need to disassemble the second part using a special key (it is also included in the latch handle kit), namely, press the inner latch located on the side of the handle, and then remove the decorative strip with the same key. Now we install the inner lining on a square rod installed on the other side of the door leaf, after which both parts of the structure must be firmly pulled together using the fastening screws also supplied with the latch. Next, we apply the removed decorative strip to the hole and insert the handle into the hole. There are two options for inserting, depending on the shape of the lock - if it is beveled, then when you install the second handle into the door, you will hear a click, meaning that the mechanism is in place. If the shape of the retainer is not beveled, then for the final fixation of the handle, press it.

And the last step in installing the door latch handle will be the installation of the striker on the door frame. To designate a specific place where the "tongue" of the latch will touch the jamb, you can, for example, mark the tip of the "tongue" with a washable marker, then close and open the door 2-3 times, leaving a "tongue" mark on the door frame. In this place, you will need to drill the appropriate recess, then attach the striker to the resulting hole and circle it with a pencil. Similarly to making a groove on the end of the door, use a hammer and a chisel to make a groove for the striker so that it is also flush with the surface of the jamb. After that, using an awl, it is necessary to mark the places where the holes for the screws will be, drill them, observing the same rule as in the case of the door end - the diameter of the holes should be slightly less than the diameter of the screws themselves. Then, using a screwdriver or screwdriver, we screw the striker to the door frame and enjoy the results of the work done.

At the long-awaited final stage of the renovation, interior doors are being installed in the apartment. In most cases, there is simply no need to use locking locks for such doors. Therefore, the latches cut into the door leaf. The article will talk about the design and installation features of door latches with a latch.

Features and varieties

Devices with a latch for interior doors by type of installation are external and mortise. The first type of latches are much easier to install, assemble and disassemble if necessary. The downside is that they significantly spoil the appearance of the door leaf. Therefore, it is the mortise fixing mechanisms that are in greatest demand.

Such latches for interior doors are presented on the market in a large assortment. Depending on the wishes and purpose, you can easily choose the optimal type of fixing device. According to the principle of operation and design features, mortise door latches are divided into several groups.

Magnetic

The door locking device consists of two parts: a metal plate and a magnetic element. The magnet and plate are placed on the side of the door leaf and on the jamb. The principle of operation of such a lock is very simple: when closing, the magnet attracts the metal element, thereby holding the door in a stationary closed position. A fixed handle is used to open doors with a magnetic locking element.

The second type of clamps of this type are models where the magnet is made in the form of a movable tongue. The advantage of this latch is that it is practically silent. Its characteristics, such as smooth operation, long service life, are also in great demand and are convenient.

Fale

Such a mortise mechanism has a movable pull-out tongue with angled contours. A plate with a groove is attached to the jamb. When closed, the tongue enters the groove and fixes the position of the door. Opening occurs when pressing on the movable handle, which leads to the extension of the tongue from the groove, releasing the door leaf from fixation.

Roller

Instead of a tongue, these latches use a spring loaded roller. When closed, it enters a small recess and prevents the door from opening. Such latches can be set in motion with a fixed handle with some force. There are also models that can be opened by pressing the lever handle.

Latches with locking latch

Usually mechanisms of this type are installed on the door to the bathroom or the bathroom. Their peculiarity is that they are equipped with a special blocking element. When the block key is turned, the latch stops opening when you press the door movable handle. Thus, the room is protected from unwanted intrusion for a certain time.

How to choose?

To purchase a quality interior door locking device, you should pay attention to the following criteria.

• The quality of the latch is indicated by the smooth operation. During opening and closing, there should be no jams or clicks.
• It is best to choose a device with medium stiffness springs. Weak springs can eventually stop holding the door leaf, especially if it is quite heavy. And mechanisms with tight springs will require effort to open the door.
• Examine the product carefully and evaluate its appearance. The body and parts should be free of scratches, cracks, chips, traces of chemical damage, rust, paint defects.
• Tactile perception is also important. The handle should be pleasant to the touch and fit comfortably in your hand.
• Try to find the specifications that best suit the operating conditions. For example, if the door leaf is very heavy and massive, you should choose a latch made of extra strong materials. The data on the locking mechanism can be found in the product data sheet.
• It is best if handles and latches are made in the same style in an apartment or house. It is also important that this element matches the design of the doors. Interior designers do not recommend using latches, handles and hinges in different colors.
• Decide on the function that the locking mechanism should perform. For installation on a door to a bathroom or a bathroom, it is best to choose a lock with a latch. For the bedroom and children's room, a quiet magnetic lock would be a good option.

Self-installation

The installation of the latch into the door leaf is almost identical to the process of cutting in a conventional door lock. This work can be done by hand. The mechanism is installed in the door at a distance of 1 meter from the floor. It is at this height in the door leaf that there is a wooden bar, into which the fixing mechanism is installed.

To cut the device into an interior door, you will need the following tools and materials:

• drill and a set of drills (feather, for wood);
• wood crowns;
• electric screwdriver or manual screwdriver;
• chisels, medium and narrow in width, a router is a good alternative for making a cut under the bar, but it is not found in every home toolbox;
• a hammer;
• pencil;
• ruler or square;
• a knife for carpentry work or a sharp clerical.

At the first stage, it is necessary to make markings on both sides of the door leaf. First, the height from the floor is measured, equal to 1 meter. Then the distance corresponding to the size of the latch to be cut is laid. Most often, the locking mechanisms have a standardized height of 60 mm or 70 mm. For greater accuracy, it is better to attach the locking device itself to the door and mark its extreme values.

Next, you need to drill a wooden bar. To do this, select a tip drill that matches the size of the latch mechanism. You need to drill to the depth of the drill blade. The next step is to make a pothole for the plank. The procedure is performed using a chisel. Previously, the veneer from the door leaf must be removed with a sharp clerical knife.

For the handle, you need to make a through hole in the bar. For this, a wood crown is used. A pothole is made from the end of the door for a tongue or roller lock. The cutouts are neatly aligned with a chisel. The device is installed in the door leaf. This must be done from the end of the door. The whole mechanism is fixed with screws or self-tapping screws.

The door handle is assembled into an installed and fixed mechanism.You must first disassemble it. Next, you can install decorative overlays. The final stage of installing the door latch is to mount the striker on the jamb. To do this, close the door and mark the position of the locking tab or roller on the jamb. This mark needs to be transferred to the box.

You also need to measure the distance from the bottom edge of the pothole in the door rail to the center of the latch. Transfer the size to the opening box. According to the measurements obtained, cutouts are made for the tongue and striker. The strip is attached to the door frame with self-tapping screws.

For reading 8 min.

The latch is an obligatory element of the PVC profile balcony door hardware. For a home craftsman, information about its purpose, classification and the principle of operation of each type will be useful. Also, advice from the practice of operating balcony latches will be useful.

The purpose of the latch

Plastic door latch is a very useful, convenient and functional part of modern door hardware. A simple principle of operation, similar to the work of latches on the doors of kitchen cabinets, allows you not to be distracted by monitoring the position of the door. The latch mechanism is designed for the free opening of the door by a person (if necessary) without the application of any serious efforts. However, strong gusts of wind do not disturb the closed position of the door leaf. Keeping the plastic door from swinging open while the door lock mechanism is in the unlocked position is the main task of the installed latch.

Another, everyday, name of the mechanism is the smoker's latch. The explanation for this is simple: it is enough to slam the door on the latch and the smoke will no longer be drawn into the living space; tight closing of the balcony door with a lock is not required for a short visit to the balcony or loggia. When using a one-way lock (its handle is located on the side of the room) and there is no latch, the door cannot be closed when leaving the balcony. So, the usefulness and necessity of installing a latch on a balcony door are obvious.

Types of door latches

The main difference between the latches used is in the locking mechanism. On this basis, the following types are distinguished:

Sagging of the door leaf, its distortion, change in the geometry of the frame structure can disrupt or make it impossible for the correct functioning of the roller and latch latch. The working latch (in the form of a roller or beveled tongue) must fit exactly into the catch of the striker mounted on the frame. The emergency setting consists in adjusting the door leaf with the screws of the fittings. In the process of adjustment, the position of the door relative to the frame opening is adjusted. In this case, the canvas can be raised, lowered, shifted to the right and left its top or bottom, and the force of pressing the opening sash to the frame can be adjusted. If this adjustment did not help to establish the correct operation of the latch (in general, this is very rare), you will have to dismantle and reinstall one of the parts of the mechanism. Usually they move in the right direction and fasten the strip with a groove.

The magnetic latch is not a problem in this regard. With a verified initial installation, its correct and reliable operation will not change from a slight distortion or subsidence of the door.

Installing the magnetic latch takes a few minutes

Another characteristic difference between latches. If the fale and roller close with a characteristic click, then the magnetic ones almost do not disturb others.

Due to the fact that the functional elements of the latches are attached to the end part of the frame and door profile, they are not visible from any side of the view. This feature helps to maintain the strict classical aesthetics of not only the door, but also the entire structure installed in the opening.

Maintenance of all types of latches is very simple. From time to time, their mechanisms are wiped from dust, dirt, debris and greased (except for the magnetic latch plates) with a special tool for window fittings. Any silicone grease or regular machine oil (spindle) will also work. The main thing is to be sure that the used lubricant does not include resins, acids and other aggressive substances.

Outside handle

Handle - plastic petal

To close, or rather to pull, the door from the street side, it is imperative to provide a special external handle. Made of metal, more often - of durable plastic, the handle visually resembles a shell or petal in shape. A plastic shell is much nicer tactilely, especially in the cold season. But it is easier to break it with careless use, and the material itself tends to deteriorate with prolonged exposure to sunlight, negative temperatures and other external factors. The main advantages of a more expensive metal handle are resistance to mechanical stress and a long service life. Typically, the outer door pull handle is positioned at the same height as the swing handle of the lock. This position is very convenient for closing the door.

It is possible to dispense with the outer shell handle only if the door lock mechanism is two-sided, that is, the inner and outer rotary handle of the lock are required.

Double-sided handle on a plastic door

The choice of external handles in specialized firms and construction supermarkets allows you to choose a copy with a convenient ergonomic shape and the desired color.

For self-assembly, replacement of latches, it is advisable to use screws: not shorter than 30-35 mm - for fastening the roller cylinder with a safety margin; no longer than 19 mm - when installing the external handle (this ensures that the screw does not reach and does not damage the glass unit during installation or further use of the handle).

Installing the latch

Getting started, you need to be sure that in the near future its position relative to the frame opening will not change. If necessary, you will have to independently set the position of the door leaf and the pressure to the frame when closing with the rotary handle. The door hinge screws will help with this. Now we proceed to the main installation. A screwdriver or a more convenient screwdriver will be enough from the tool; take a pencil for marking.

The easiest way is to install a magnetic latch. No special adjustment or precise installation is required. Both strips are simply attached at the same level - on the end of the door and the frame profile. A slight displacement of the relative position will not interfere with the correct operation of the latch.

Opposite the latch, make a mark with a pencil and fasten the striker in the center of the groove

Another thing is the mechanism of the roller and latch latch. In both cases, the exact position of the slotted strip relative to the latch is required. Without hesitation and measurements, we attach the latch itself to the seat of the balcony sash. Opposite its center, we make a risk with a pencil and bring this line outward so that it is visible when the door is closed. Having closed the door, we note a similar risk at the same level, but on the frame. At this height, the grip center of the striker should be located. Now we fix the bar with a lock at the mark with one screw and check the correct operation of the mating elements. If the result is negative, the bar is shifted and the performance is checked again. If further adjustment is not required, the bar is also attached with a second screw.