Swing gate drive: DIY manufacturing and installation

Recommendation points

• Preparing the gate and attachment points
• Manufacturing a drive from car window regulators
• Selection and calculation of engines
• Stud for homemade drive
• We increase the hardness of the stud
• Increasing the thread of the stud
• Assembling the actuator
• Sizing the actuator
• Assembling the sliding part
• Plugs and swivel joints
• Outer tube of the actuator
• Motor installation and final assembly
• Wiring diagram
• Equipment selection
• Secondary circuits and automation

The owners of sliding gates do not experience any particular difficulties in completing the sash with a drive mechanism on their own, but when it comes to swing gates, much more effort and knowledge is needed. Today we will talk about drives for swing gates and their DIY assembly.

There are three main types of gear transmission that convert the rotation of an electric motor into a translational motion with a high torque. The design of the mechanism can be performed:

• in the form of a gear wheel;
• using a screw pin;
• using rack and pinion.

On these three types of kinematics, it is quite possible to assemble your own mechanism even at home.

The design of a homemade actuator proposed below is not afraid of moisture and dirt, it has a very high effort when moving.

Please note that when the gate is closed, such a homemade drive acts as a lock: it cannot be opened from the outside by pressing on the gate leaf.

Preparing the gate and attachment points

Almost any swing gates or doors can be equipped with a drive, but it is better to plan the installation of the mechanics in advance. This applies to the installation of secure mountings for the drive. They have the form of metal plates with holes at the ends, one of which is fixed strictly perpendicular to the sash, the other is located on a post or fence in the same position.

When installing, the plates must be oriented horizontally and be on the same level. It is very important to take into account the high pulling force of the drive, therefore the best way to attach the plate to the gate is welding. Plates can be fixed to stone and brick pillars with metal anchors, but it is much better to make embedded elements of steel during the construction phase.

The easiest way is to mount the operator on gates that open to the inside, so that all actuators are in a protected area. A cable must be laid in the door opening, so lay a 32 mm plastic pipe under the road surface in advance.

During the mounting phase, you will define the first basic parameters of your drive. Measure the distance between the centers of the holes in the mountings when the gate is closed and open. The latter is the length of your actuator in the folded position, and the difference between the measured distances is the amount of travel of the device..

You can also measure the opening and closing force of the gate with a hand-held spring scale. Pull the gate wing mount in the direction of the opposite mount, this will help to most accurately select the motor power.

Manufacturing a drive from car window regulators

Lightweight gate leaves can actually be set in motion by a drive from modified window regulator mechanisms. The advantage of this method is its relative simplicity and almost silent operation of the drive. The disadvantage is the limited tractive effort due to the small working stroke of the mechanism.

There are two types of window regulator designs suitable for use as a gate drive:

• the role of the movable element is played by the gear rack;
• based on the work of a gear.

In both cases, the drive end is mounted on a metal platform, which is rigidly attached to a post or fence. In this case, the metal rail must move parallel to the plane of the gate and extend towards them..

The lift mechanism needs some work: the installation of an elongated metal rod for the rack or the knee lever for the gear wheel. The joints of the rod with the drive and the gate, as well as the two parts of the knee lever, must be made in the form of a fork hinge, following the example of a door closer.

You can ensure good mobility and no backlash if one side of the connection is made in the form of two folded plates, the gap between which is equal to their thickness. The plate of the second part of the hinge will enter this gap. Both elements are connected with a finger or a bolt with a self-locking nut.

The main difficulty in using window regulators is to find the most advantageous position of the drive, hinge and points of attachment of the rod to the gate. You can confidently do this experimentally, first setting the gate in the open position and slowly closing it, monitor the behavior of the drive structure. Do not forget that after installation, the mechanism needs a protective cover.

Selection and calculation of engines

As an activator of movement for swing gates, it is advisable to use different types of gearmotors. If we are talking about small gates of low weight, motors of cordless screwdrivers, drives of car wipers, window regulators, etc. will cope with the task. Another question is how you plan to make a clutch for the shafts of such motors.

You can also choose a suitable unit from a wide range of shop gear motors, this gives you more freedom in determining the required torque. So, let’s say the measured closing force of the heavy gate leaf is 13.5 kg on the manual canter scale. Each kilogram corresponds to 9.8 N, which means that the traction force is 132.3 N. In the case of a rack or pinion drive, this value must be divided by the diameter of the drive wheel, this will be equal to the engine torque.

In the design of the “nut-screw” type, there is a reduction, therefore, additional recalculation is required. Let’s say you have chosen an M18 stud with a pitch of 2.5 mm. This means that in one revolution around a circle with a diameter of 18 mm, the nut makes 2.5 mm of translational movement, so the gear ratio is 7.2: 1. Accordingly, if we divide the gate opening force by the transmission coefficient, we get the desired value of the force on the motor shaft: 132.3 / 7.2 ~ 18.4 N or slightly less than 1.9 kilograms with a hairpin radius of 0.9 cm. the torque value for the engine is 1.69 kg / cm.

This is a rather rough calculation that does not take into account the frictional force in the screw drive and other losses, but it helps to determine the minimum allowable motor power. To compensate for energy losses, it is recommended to provide a power reserve of 100-250%.

It is also necessary to calculate the speed of rotation of the shaft. To do this, divide the stroke length by the thread pitch of the screw drive, and you will get the number of revolutions required to fully open the gate. When using a rack and pinion, the calculation is determined by the ratio of the number of teeth of the rack and the drive gear.

Stud for homemade drive

Heavy doors require a drive with a high applied force. Such work is within the power of factory-made drives, but you can create an analogue with your own hands..

The main difficulty is finding a suitable stud. Standard pins are not suitable for the drive: they are made of soft metal, so over time the thread becomes unusable. The way out of the situation is to independently increase the hardness of the metal and the number of contacting turns of the screw thread.

We increase the hardness of the stud

The first problem is solved by hardening. The required heating temperature is provided by ordinary charcoal, it also partially carburizes the metal. Fold a furnace made of brick and cast-iron grate, heat the fuel until the coals are completely burned out. The hardening temperature is 700–800 ° С, which corresponds to the rich red color of the metal. Exposure at this temperature is 13–15 minutes, after which the part must be cooled in used oil. The pin must sink completely and simultaneously along its entire length, therefore, spread the steel pipe along the longitudinal seam, plug the ends and use this tray as a quenching bath. The hairpin needs to be slightly shaken in the oil all the time it cools, then take it out and put it back on the coals without wiping it to release the metal. Now the heating must be performed up to 200-250 degrees, until the metal turns gray with a pronounced formation of scale. After 3-4 minutes of exposure, the product must be cooled in water.

Increasing the thread of the stud

To make a special nut, screw 2–3 standard nuts on the stud tightly, but not tighten. Align the edges of the nuts and clamp the assembly very tightly in a vise. Weld the nuts together on all edges and grind the product with a grinder to the same size.

Instead of a complicated hardening procedure, you can spend time looking for rolling studs and nuts for them. This metal has all the necessary characteristics. In addition, you can choose a thread with a trapezoidal profile: it is much stronger. You can also find a product with a larger thread pitch, which will shorten the operating time of the mechanism..

Assembling the actuator

Sizing the actuator

The actuator has a telescopic device, for its manufacture you need two steel pipes, one of which enters the other without strong play. You can use a square or round tube, there is not much difference. Inside both pipes there should be no traces of rust and scale, so it is better to get new ones.

As for the dimensions of the pipes and studs, you must calculate them yourself, based on the measurements taken. Suppose, when folded, the length of the drive is 110 cm, and its working stroke is 50 cm.This means that the length of the outer tube will not exceed 100 cm, a smaller tube 80 cm long will be inserted into it, and the length of the stud will be a full 110 cm or more, depending on the method of motor mounting. At the same time, in the open state, the drive pipes will have an overlap of 30 cm.

Assembling the sliding part

Pass a stud with a nut screwed onto it through the smaller pipe and center it on the longitudinal axis of the pipe. To confidently center the stud, do not oversize pipe. For example, if you are using an M18 nut with a wrench size of 27 mm, select a pipe with a nominal diameter of 25 mm. You just have to grind the nut evenly so that it fits snugly into the pipe. Fasten by welding. Welding is optional on the inside, but you can do this by cutting a “window” into the pipe. When the nut is secured, unscrew the stud from it.

At the end of the stud, an axial-axial bearing with a cage closed on both sides must be fixed. The outer diameter of the bearing should be approximately equal to the inner diameter of the pipe. The bearing should slide inside the pipe without significant resistance, the gap between it and the wall should not exceed 1 mm. If the bearing fits too tightly, carefully sand the end of the outer race with sandpaper. On the stud, the bearing must be firmly clamped between the two nuts. Between them and the bearing, it is imperative to lay 1-2 washers on both sides so that nothing interferes with rotation. Liberally lubricate the stud with lithol and insert it from the free side of the small pipe, then screw it into the welded nut. Perform several test runs along the entire length: the bearing should slide freely inside and not wedge.

Plugs and swivel joints

Next, it’s up to the stub. It needs to be made from a metal blank, the diameter of which is slightly less than the diameter of the pipe. To make the drive serviceable, make two or three countersink holes in the pipe, cut a thread for the fastening screws in the corresponding places on the plug. Weld two steel strips with a through hole to the end of the plug so that the gap between them is slightly larger than the thickness of the fastening on the gate leaf. Consider the distance “stolen” by the plug when calculating the total length of the actuator in the stowed position. Before installing the plug, push 50-70 grams of lithol into the pipe, then tighten the stud so that the bearing enters the pipe by 5 centimeters, add grease again and plug the pipe.

Outer tube of the actuator

The stud from the pipe must be unscrewed completely until the bearing rests against the nut. Then the inner pipe is inserted into the outer one, and the hairpin is screwed in 5-6 turns.

Next, you need to decide on the method of mounting the motor. Ideally, the cylindrical motor housing should be secured inside the pipe with clamping screws. If you are unable to select a motor of the correct size, weld a piece of larger pipe, steel strip or metal angle to the rear end. This way you can secure the oversized engine in any convenient way..

Important: the distance from the surface of the platform to the central axis of the pipe must be equal to the height of the motor shaft. Position it so that it aligns with the stud as coaxially as possible.

Motor installation and final assembly

Connect the motor shaft to the stud using a coupling. You can purchase it from the arsenal of components for the motor or make it yourself from two small tubes nested one inside the other. Lubricate the stud a second time and secure the engine to the site. Then, by rotating the inner tube, shorten the length of your actuator to the standard open position. Lubricate the entire surface of the inner tube with lithol and fold the actuator completely.

If you are going to mount the motor inside the pipe, sink it 5–6 cm deep and use a plug similar to the first one. Pass the motor power cable through the hole made in the bottom of the pipe so that no water can flow inside. Or make a hole in the plug itself. In both cases, it will be wise to install stuffing box entries.

If the engine is mounted on a platform – weld the fork end to it, make sure that the structure is sufficiently rigid and protect the engine with a shroud. Now you just have to install the actuators in place by connecting the fork ends of the plugs with the fasteners on the gates and posts. This can be done with a cotter pin or a self-locking nut bolt..

Wiring diagram

Equipment selection

The engine is controlled according to the classic reversible scheme, but there is one detail. It is clear that swing gates have a limit bar, so the leaves must be folded in a certain order. When the sash is torn off, the sash begins to move without a bar first, but it should be the last to close. This can be implemented in different ways, the most reliable is a relay with a turn-on delay.

The assembly of modular devices includes:

• four contactors Hager ES424 (DC24V 4NO);
• two time relays Hager EZN001;
• differential automatic machine Hager AD906J;
• MeanWell DR-120-12 power supply unit.

The equipment is assembled in a plastic box Hager VECTOR VE118DN with a degree of protection IP 65. The circuit is designed to power two powerful IG-90GM geared motors at a voltage of 24 V.

Power is supplied through the differential circuit breaker to the L and N terminals of the power supply. From its reverse side, two 24 V DC lines are removed, each supplying two paired contactors: power is supplied to the input terminals of one of them in reverse polarity. The outputs of the pairs of contactors are connected in parallel and supply voltage to the geared motors.

Secondary circuits and automation

The contactor control circuit operates at a constant voltage of 24 V. The positive power wire passes through the break contacts of the “stop” buttons and connects to the break contacts of the control buttons, from which power is supplied to the normally open contacts of the opposite buttons. From each button, voltage is applied to two pairs of starters, while one of the normally open contacts serves as a pick-up coil. The control circuit of the direct starter of the first pair and the reverse starter of the second pair is opened by a normally open relay. The relay is powered from the normally open contact of the starter of the other group. Thus, a time delay is performed for the successive movement of the leaves..

Automatic stop of the motors is carried out by actuation of the end reed switches. They need to be installed along the direction of movement of the actuator, and small neodymium magnets should be glued to the surface of the inner pipes. Thus, when the actuator is fully folded or its stem is extended, the reed switches are triggered, which close the supply circuit of the intermediate relay with a normally closed contact. The relay is connected in parallel and duplicates the “Stop” button.

Such a drive can also operate under the control of an automatic swing gate, the circuits are similar. Now you can easily open the swing gate without leaving the car without serious financial investments..