The device screwdrivers familiar to many professional builders who can disassemble it and competently repair. In any case, this can be done only by understanding all the details of the screwdriver mechanism, including the gearbox. This element must be responsible for the process of transferring rotation from the engine to the cartridge device, which actuates the impact mechanism of the tool.
Device network screwdriver.
The design of the punch on the gearbox has its own characteristics. The location of the gearbox can be horizontal and vertical. The heavy weight and large dimensions of perforators with the vertical position of the gearbox make them more powerful and reliable, having a greater impact force. Tools of these types are mainly used by professional builders, and not by home craftsmen. In general, the gearbox determines the mode in which the tool operates. Work of the puncher is reduced to two or three functions.
The principle of operation of the gearbox
Figure 1. A typical screwdriver gear unit.
The perforator is a convenient and easy-to-use device, the beginning of its use is associated with space flights, where it was used by astronauts. New models of screwdrivers are produced, so the demand for them does not fall. This device is suitable for various household trifles, as well as repairs.
The action of the screwdriver gearbox resembles the process of the drill gearbox, the distinctive characteristic of which is the equipment of the part and gear ratio. The gearbox of any of these tools requires regular inspection. The uninterrupted operation of these devices is associated with a periodic check of the working condition of the gears and the lubrication of gearboxes, which sometimes require replacement.
The gear mechanism includes cylindrical, bevel and worm gears. The gear ratio of the gearbox is constant. Regulates the number of revolutions of the cartridge and the frequency of shocks using an electronic controller. There are models of devices that have two-speed gearboxes. During operation, the device must not be overloaded, that is, it cannot be operated for longer than 15 minutes. Every quarter of an hour, the perforator should cool down, since the device cannot operate continuously.Back to table of contents
What is a gearbox?
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Types of gearboxes for screwdrivers
Scheme of the internal device screwdriver.
There are two-stage and three-stage gearboxes for screwdrivers, which is determined by the number of elements in the mechanism. The carrier and the satellites are interrelated with the shaft of the gearbox on which the device cartridge is attached. These parts are included in the ring gear, which must be firmly fixed in the gear housing.
To secure this gear use protrusions resting on special protruding balls, to which the ring is attached. At the expense of the ring, the balls spring, which is also affected by the presence of a spring related to the load limiting system. The degree of tension of the spring depends on the position of the mechanism regulator.
Depending on the material manufacturing satellites, gearboxes are divided into metal and plastic. It all depends on what tool is used: professional or amateur. If the modification of the perforator is a household one, then the provision of a rotating moment, reaching up to 10-15 Newton meters (Nm), occurs due to plastic gears.Back to table of contents
Features assembly gear
Device cordless screwdriver.
In addition to the ring gear, the gearbox includes a sun gear and a central gear that is pressed onto the armature shaft; an annular gear cylinder having an inner circle along which the satellites can move due to the teeth on the circle. Satellites also have teeth. Rotating around their own axes and the axis of the central wheel, they can constantly catch on while working with the tool. Satellites are planted on each of the pins belonging to the carrier.
The optimum speed of rotation due to the metal satellites is ensured by the operation of the gearbox with the maximum torque, which ranges from 25 to 150 Nm. Depending on the torque, screws of a certain length are used, suitable for various materials, that is, wood, steel or concrete. The presence of the regulator in the device allows you to make the choice of the most suitable torque in order to perform work using a perforator.
Possibilities of household screwdrivers.
Often the gearbox is a fairly powerful steel element, but plastic models are cheaper. The motor shaft of the device is besieged by gears, and the gearbox has gears in the amount of three pieces. This drive is called planetary. The gearbox itself is quite simple to take out of the case, it can be assembled without much difficulty.
So that the gears do not fall out of the gearbox, they are inserted at an angle. This prevents gears from falling out when they are tilted. The gearbox is removed from the ratchet with the housing. Fixing the cartridge occurs at the expense of the screw, and for unscrewing it provides for the thread of the cartridge, which is right.Back to table of contents
How to properly disassemble the gearbox?
The action of the percussion percussion mechanism is based on the transfer of rotational motion emanating from the engine to the cartridge. A high-quality repair will be able to be performed by a professional worker who does not harm the device and his own health, which will be safe thanks to his work experience.
Table of characteristics of screwdrivers.
To properly disassemble the screwdriver of any model, will require detailed knowledge of their design. The main details of the planetary gear are the following elements:
These parts and components may consist of plastic or metal. In the process of disassembling the gearbox, the cartridge snaps off of it due to the spring controlling the degree of compression. Behind the cartridge is a cone, which is turning. The spring coming from the cartridge generates pressure on the balls in the housing. From the balls the pressure goes to the gearbox. When disassembling, they get enough sleep, so disassembly should be carried out on the cleaned surface so that no part is lost.
The ring gear has rotating satellites inside, which drive the sun gear of the engine. Drove punch has a lower speed than its engine. The first carrier transmits torque through the rotation of the sun gear to the second. This allows you to reduce the speed of the second carrier associated with the shaft of the cartridge. The work of the three-stage gearbox is similar, but with the addition of an additional planetary gear.
Electrical components of the screwdriver.
In any case, the sequence of disassembly of the screwdriver gearbox includes the following steps:
- Removing the cartridge.
- Unwinding the case.
- Disconnecting the gearbox from the engine.
- Removing the plate.
- Removal of all parts from the housing.
- Unscrew all bolts that connect both halves of the gearbox.
- Correction of the diameter of the spring with the use of pliers in the smaller direction in order to improve the inclusion of transmission.
- Analysis of the coupling by removing the retaining ring, washers, bulk bearing.
- Removal of the shaft.
The gearbox device consists of three gears that receive rotation from the central gear of the motor shaft, as shown in fig. 1. The outer sleeve is driven by the existing threaded teeth, meshed with gears, which belong to the first and second steps of the reduction.
The punch device is equipped with a critical load mechanism that has a disk with a certain number of holes. They are drilled so that they can be inserted into the spring-loaded fingers having ends, hardened by high-frequency current. This design has a hardened liner edge, which refers to the gearbox.
The sleeve has grooves made specifically for the fingers of the first disc. The finger mechanism is adjusted with the usual twisting and unscrewing of the nut threads, which is associated with the strengthening or compression of the springs of this mechanism. Excess force is associated with pulling the ratchet of fingers, so the process of rotation of the cartridge in the mechanism of the gearbox stops.Back to table of contents
Causes of screwdriver breakdowns
When buying a screwdriver, it should be borne in mind that the manufacturers of this type of tool do not manufacture repair kits for the device.
Almost all the repair gear after disassembling the tool will be reduced to its cleaning and lubrication.
A common cause of a screwdriver breakdown is the ingress of spears into a sliding bearing.
If parts that have worn out are found, then the entire assembly should be changed. High-quality screwdriver work is not associated with the presence of grease in the gearbox in excess.
A screwdriver after a long use can have not only electrical faults, but also mechanical ones. These types of breakdowns can be associated with the appearance of uncharacteristic sounds indicating that the sleeve or bearing is in a worn condition. Therefore, after the inspection, damaged parts are detected, which are then replaced with new elements.
If during the operation of the screwdriver there is a wedge that will be accompanied by a rattle, then this fault can be attributed to poor quality of the gearbox.
The main causes of mechanical damage:
- The presence of damage to the bearing or sleeve reducer.
- Worn gear teeth or coupling.
- Deformation shaft gear.
- Damage to the pin with which the satellite was fixed.
- The beating of the cartridge.
If the beating of the cartridge is detected, a bent shaft of the gearbox may be detected. However, this may be associated with a large bearing wear. Various models of screwdrivers have not only bearings, but also copper bushings as part of their device.
The operation of the gearbox couplings is associated with the constant wear of the couplings having teeth. The operation of the tool as a whole, associated with certain modes, may be accompanied by a weakening of actions related to the high-quality operation of the couplings, their slippage. These items, like washers, will be worn.
Recovery of these elements is not possible, since they cannot be restored after their condition has been determined. Therefore, you should purchase new parts for the gearbox and replace them with old ones.