Demolition hammer and its operation

Demolition hammer and its operation

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Not so long ago the jackhammer was used exclusively in the mining industry. But with the development of technology and the improvement of the mechanization of manual labor, this tool has moved to other areas of production. Today, a rare construction works without this powerful assistant, making the work less difficult and expensive. Thanks to the use of a shock hammer, labor productivity increases many times. There is an opportunity to solve complex tasks related to the reconstruction and demolition of old buildings, the construction site for the construction of new houses.

Content

  • 1What is a jackhammer, the principle of its action
    • 1.1Breaker assembly
    • 1.2Video: the principle of operation of this type of equipment
  • 2How to choose a quality
    • 2.1Video: Review of jackhammers
    • 2.2Table of Classification of Devices by Purpose
  • 3How to use the device, safety
  • 4Technical maintenance of a jackhammer
  • 5Diagnosis of breakdowns and repairs
    • 5.1Video: disassembly and assembly of electric jackhammer Makita
    • 5.2Table of possible malfunctions and how to eliminate them
  • 6Video: self-made pneumatic hammer
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What is a jackhammer, the principle of its action

The device is a percussion instrument designed to work on breaking and splitting rock sedimentary rocks, concrete structures, asphalt, etc. The hammer is controlled by the operator manually, the direction of impact is controlled, the frequency and duration of the impact on the processed surface. Since the force effect is transferred to the working organ (spade, shovel, killed, etc.) from the striker, driven by an external source of energy, the device belongs to the mechanized class tools. The drive can be

  • electric;
  • pneumatic;
  • hydraulic;
  • gasoline.

The number of impacts varies from 15 to 45 Hz. (i.e. 15-45 strokes per second).

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In addition to manual jackhammers, there are machine tools that use a similar operating principle. They are used in the development of rocks in mines and open pits. The inventor of machine tools is the French engineer Germaine Sommeye (late 50s of the 19th century).

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Mobile jackhammer in shaft digging

Breaker assembly

Despite the diversity of species, their principle of operation is no different. The working part is a chisel, a pike or a slotter blade. This, as a rule, made of high-strength steel hexagon, pointed at the end. In action it leads a bojk which receives a pulse from the drive mechanism. The bojok and the piston are established in a sleeve. Between them is the air space, which is compressed, pushes the fighter towards the peak. Such a design is necessary so that the breaking force does not have a direct application to the drive mechanism. Otherwise, blows of 30-50 kJ. would quickly destroy the engine's rod. During the return stroke of the piston, a low air pressure is formed inside the sleeve, which "draws" the boom into its original position and the cycle is repeated again. Regardless of the design solution of the drive, the mechanical part of the bump stop remains unchanged.

Various modifications of pneumatic driven pneumatic hammers

Video: the principle of operation of this type of equipment

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How to choose a quality

In order for the jackhammer to serve for a long time and not to break, it is necessary to make the right choice of the model. The technical characteristics of the tool must correspond to the tasks that are before it. Too powerful and dimensional equipment consumes a large amount of electricity, requires maintenance in specialized workshops and expensive consumables. Insufficiently powerful - can not cope with a given amount of work. Therefore, when choosing it is necessary to take into account all the details and nuances of the forthcoming load on the tool. The following technical parameters are considered to be the main criteria that should be taken into consideration when choosing a bumper.

  1. Dimensions: length, width, height. The larger the linear dimensions of a mechanical hammer, the correspondingly, the greater the power and its resolving power. However, indiscriminately chasing the "big and powerful machine" is not always justified. In some situations (for example, in the conditions of apartment repairs) it is more reasonable to use the equipment compact, which allows to work in cramped circumstances.
    When hollowing holes in concrete ceilings, a hammer with an increased impact force
  2. The weight. On the one hand, the greater the weight of the tool, the more pressure it exerts on the surface to be destroyed. But if you have to break the wall or elements of the ceiling, the load is completely on the hands (and feet) of the user. In this case, preference is best given to light models with high impact indicators.
    When carrying out work in the horizontal plane, the weight of the tool must be selected in accordance with the physical capabilities of the operator
  3. Frequency of impacts. This is one of the main indicators, which directly affects the performance of the tool. It can be measured in Hertz (Hz) or revolutions per minute (rpm). The number of Hertz shows the number of beats per second. Turns per minute indicate the frequency of translational movement of the rod for one minute.
    The impact frequency and the energy of a single impact are displayed in the hammer specification sheet
  4. The energy of a single stroke. The magnitude that characterizes the productivity of energy costs. It is measured in Joules (J), which is equal to the displacement work, kg. to a height of 1 m. In simple terms, impact occurs when the weights fall freely in 100 grams from a height of one meter. If the passport specifies the impact energy of 50 Joules, then from a height of 1 m. dropped 5 kg weight, pointed at the end.
  5. Drive unit. As indicated above, the drive mechanism of a jackhammer can be different. For domestic conditions, the most common was the electric drive. In locksmith workshops, pneumatic bumpers are often used. For "field" conditions, autonomous gasoline vehicles are used. Hydraulic units operate in large production facilities, in mines and in pile driving.
    Industrial hammer on the basis of a hydraulic drive of a tractor
  6. Power. This is the amount of electricity consumed by the device during operation. In the passport is designated in watts and kilowatts (Tues. and kW.)
    Gasoline drive hammer allows you to work offline
  7. Vibration level. Oscillations that produce destruction are spread not only towards concrete, asphalt, stone, etc., but also partly to the operator controlling the machine. With constant exposure to the hands, there are such professional diseases as numbness of limbs and somatic constriction of blood vessels. Each model is certified in accordance with the norms of the permissible level of vibration. A note on this is put in the passport (in the international system of ISO standards, indicating the numerical value in m / sec2)
  8. Sound pressure level. Measured in decibels (dB). As a rule, most professional hammers during operation exceed the safe noise level, which is determined within 70 dB. That's why you only need to work with this equipment in headphones.
    Sound-absorbing headphones protect hearing organs from overloads

In addition to these parameters, it is sometimes useful to take into account additional technical characteristics.

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  1. Transport weight of the tool. This is the weight of the tool, packed in a case together with consumables and spare parts.
    Factory case for hammer transport
  2. Shank type and dimensions. There are several types of baits that differ in their rear part - the shank. Its configuration depends on the attachment mechanism. The most common are hexagonal shanks, under SDS-cartridge and shanks with groove. Sometimes combined cartridges are used, they can be changed as needed.
    Different configuration of snap-on hammer
  3. Parameters of the consumed energy (or energy carrier). In the event that the jackhammer has an electric drive, the mains voltage must correspond to the passport data. In the overwhelming majority of cases, this is 220 V, 6 A and 50 Hz. However, there are exceptions. The pneumatic tool is driven by compressed air from the compressor. If the air pressure necessary for operation does not correspond to the nominal pressure, the bump stop will not develop the required power and may fail. In gasoline engines, it is important to follow the manufacturer's recommendations for the preparation of the working mixture (gasoline grade, percentage of lubricant and fuel).
    Oil for the preparation of a gasoline mixture intended for two-stroke engines
  4. Additional functions. These are devices that facilitate operation and contribute to greater efficiency of work. These include the fixation of the start button, anti-vibration system and the frequency limiter of strokes at idle. The latter option significantly increases the service life of the hammer. In addition, the electric mechanisms use the indicator of wear of graphite brushes, informing the user about the need to replace the electrodes.
    When graphite brushes wear out more than 40%, they must be replaced
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Especially "advanced" models are equipped with a function to protect against damage to cables. It consists in the fact that when a bit hits the conductor under tension, the opening relay is triggered and the engine of the jackhammer is switched off. The device helps out in cases where dolobyzhka is conducted in old buildings, where the wiring can be in the most unexpected place.

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With frequent use of a hammer, the joints of the hands of the operator suffer most. For such users, the system of paying off the vibration is not a luxury, but an urgent necessity.

Video: Review of jackhammers

All information, as a rule, is reflected in detail in the technical passport of the product.

Attentive study of it will protect against errors of choice and annoying disappointments.

There is also a general classification of all devices for household and professional. Households are designed for small amounts of work that do not involve daily operation. Professional bumpers meet high demands. They are able to work in uninterrupted mode for a long time. The former are more accessible financially. The second cost more, which is due to the high costs of manufacturing.

A sign of performance is the size of the hammer. Below are the technical characteristics of the four basic sizes.

Table of Classification of Devices by Purpose

Size Purpose Impact energy Impact frequency Grades of jackhammers
Size number 1 Crushing, removal and detaching of materials with medium strength: clay, brick, plaster. Operation in cramped conditions, in weight. up to 30 J up to 45 Hz МО-1, МО-1Б.
Size number 2 Works of general character. up to 40 J up to 35 Hz МО-2, МО-2, ОП-2, МО-2М, ПМ-2.
Size number 3 Work with materials of increased strength, mainly vertically from top to bottom. up to 45 J up to 20 Hz MO-3B, MOS-3, IP-4613.
Sizes 4 Processing of high-strength materials, including reinforced concrete. Direction of impact - from top to bottom. more than 50 J up to 25 Hz МО-4Б, МОП-4.

When choosing a hammer, you should also consider the tool manufacturer. The state of the market is such that it is always possible to spend money for forgery. And sellers do not always know about what is inside a beautifully designed product with all the attributes of a quality product. In particular, in plastic hammers of unscrupulous manufacture plastic gears can be installed instead of metal ones. Their work will not be different, except for one - a month later plastic under the influence of loads will collapse, and the hammer will fail. Therefore, it is better to bypass dubious variants of "profitable" purchase and give preference to well-established manufacturers. These include brands with international recognition: Bosch, Makita, Hilti and Hitachi.

Heavy Heavy Duty Electric Heater Hitachi

From the domestic manufacturers of pneumatic tools deserved respect is enjoyed by a series of bumpers and concrete breakers "MO" and "MOS produced in Tomsk. This is a real professional technique that can be used both in everyday life and at work. The advantage of Russian tools is a wide network of service and spare parts availability in retail sales.

Professional hammer of the company "Zubr"

How to use the device, safety

Working with a jackhammer has a number of features associated with the impact of negative factors on the operator.

  • increased vibration during operation;
  • increased level of dust in the chipping zone;
  • high noise intensity, hazardous to health;
  • an abundance of fine particles of solid material, emitted at high speed from under the chisel.
When working with a bumper, protective equipment is needed
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Therefore, the safety requirements include the following items:

  1. It is forbidden to work without the use of personal safety equipment - earplugs or earphones, a respirator, goggles, and also work without gloves and a protective suit made of dense fabric.
  2. It is forbidden to use a jackhammer deliberately faulty. Before switching on, the chisel fixing and tightening of the bolts on the housing must be checked.
  3. During operation, following the precautionary rules, it is necessary to hold the bump stop only for the standard handles. It is inadmissible to work with one hand.
  4. If there is an additional holder, use it for the intended purpose. The position of the body must be stable.
  5. It is forbidden to trust the instrument to minors and leave it turned on unattended. It is inadmissible to aim the tip of the chisel in the direction of other people.
  6. At the end of work, do not touch the metal part of the body with bare hands. This can lead to severe burns.
  7. It is inadmissible to use the tool for other purposes than scrap or shovel with the drive turned off.
  8. The maximum period of work of a jackhammer is limited to 6 hours. Resumption of work is permissible only after 1 hour break.
  9. When using the tool in the cold season in the open air, the lubricant needs to be warmed up. To do this, you need to turn on the device, and within 2-3 minutes. warm up at idle.

The execution of these simple rules will protect the user from injuries, and the bump - from premature wear.

Often, when using a pneumatic hammer, some users increase the pressure of the compressor supplying compressed air to the tool. They come from a simple argument that the more pressure on the piston, the greater the impact force. This is indeed so. But, unfortunately, very short time.

The compression level should correspond to the installed nominal pressure of the unit

All passport parameters of the hammer are indicated taking into account the nominal pressure - this is, as a rule, MPa. (or 5-6 atm.). When the pressure is increased to 7-8 atmospheres, the load on the piston increases sharply (by 40-60%), and this leads to a reduction in the service life of parts by half. Therefore, the conclusion is simple - instead of "squeezing" out of the hammer unusual power, it is better to choose a tool with increased impact strength.

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During operation of the electric jackhammer, sparks emerge on the collector of the electric motor. This should be remembered when carrying out work near combustible and flammable materials. In such a situation it is safer to use devices with pneumatic drive.

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Technical maintenance of a jackhammer

This is due to the simplicity of the design and purpose of a sufficiently reliable and "unshieldable" tool. Equipment repair specialists note that 70% of cases of failures are associated with overloads and unscrupulous attitude towards operational standards.

Only authorized personnel are allowed to operate the equipment

Help to avoid premature wear will help simple rules.

  1. Timely lubrication. Before installing the bit (or other attachments), it is necessary to lubricate the liner with lithol, solidol or some other heavy lubricant. Reducing the friction inside the cartridge prevents overheating and wear of the muzzle of the jackhammer.
  2. Observance of the operating mode. Every 35-40 minutes you need to take a break for 5-10 minutes. This is necessary for the hammer to cool down, and the lubricant does not boil.
  3. Carrying out routine maintenance work. The manufacturer's recommendations should be included at this point. After 100-150 hours of operation (depending on the model), you need to change the lubricating coating. Make sure that the oil does not run out of the impactor. If the leak is "chronic you must replace the gasket.
  4. Proper storage. A dry room with a positive temperature and relative air humidity of not more than 80% will be the optimal condition for the safety of all the mechanisms of the unit. Do not leave a hammer in the open air during rain and heavy frosts. If there is a transport case, it must be packed at the end of the work.
    Proper storage of the instrument is a guarantee of its safety
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It must be remembered that the new tool received from the plant must be disassembled, cleaned of grease, thoroughly washed all components in kerosene. Only after this, assembly is made and the hammer is ready for operation. The overwhelming majority of manufacturers, provides for a certain period of storage of the product and protects the tool from corrosion, covering it with protective compounds that need to be removed.

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Maintenance includes the following two types:

  • Every day, which is held every day before starting work;
  • monthly, produced once a month in stationary workshops and involving complete disassembly, washing and lubrication.
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Consumables that wear out constantly need to be changed as they become available. Chisel and peak can be sharpened independently. To do this, use a Bulgarian or a stationary grinder. It is important to maintain the correct angle of sharpening. It is forbidden to "edit" the sharpening shank - this leads to an increase in technological gaps, with all the ensuing consequences.

Diagnosis of breakdowns and repairs

Among specialists in the repair of jackhammers there is such a saying. The bump is the same Kalashnikov assault rifle, only shoots more often. Complete disassembly and assembly in the hands of an experienced craftsman occurs quickly. It is better for beginners to familiarize themselves with the device and only after that to start repair.

Regardless of which drive is at the hammer, the dismantling begins with a complete shutdown from the compressor or mains.

It is strictly forbidden to disassemble the instrument without disconnection, it is dangerous for life and health.

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The order of assembly and disassembly is described in the technical documentation for each product.

Video: disassembly and assembly of electric jackhammer Makita

Below are the most common types of breakdowns of pneumatic hammers and how to eliminate them.

Table of possible malfunctions and how to eliminate them

Possible breakdowns and ways to eliminate them
Damages, their external signs and manifestations Preparing for repair work Sequence of work execution Special tools or devices for troubleshooting
1. The jackhammer does not work
Absence of pressure, low level of air compression Control of air pressure at the compressor outlet 1. Cleaning and purging of hoses.
2. Checking the integrity of the supply hose. In case of damage, replace it.
Pneumatic hose, high pressure hose.
The channels of the trunk became clogged, the water got inside and froze Dismantling and inspection of the trunk Cleaning and washing the channel from debris, water and ice. Assembly, purging and run-in at low load. Clean flushing kerosene. Lubricant recommended by the manufacturer.
2. Reduced number of hits with a weak single blow
Use of a pneumatic hose (hose) of small cross-section or too long. Low air pressure. Air pressure monitoring. The distance between the compressor and the hammer should not exceed 20 m. The manometer.
Hose clogging due to damage Disconnect the hose from the compressor and hammer Find and remove the damaged part of the sleeve. Repair or replace the hose as a whole. Knife, clamps.
Fracture of the hose. Excessive lubrication Disconnect the hose from the compressor and hammer Eliminate the inflection. Rinse the hammer. Work at low load. Flushing kerosene, industrial lubricant.
3. Increased number of hits with a weak single blow
Increased clearance between the distributor and the receiver of the barrel. Detachment of the hammer, silencer. Removing retaining ring, retainer. Twisting the link to the stop and installing the retainer, the lock ring. Locksmith vise, special clip for retaining ring.
Clogging with foreign garbage of the node of conjugation of the stem end and the cover of the valve box. Disassembly of the hammer. Extraction and removal of foreign objects (sand, shavings, dirt, etc.) Flushing and blowing of parts. Before work, there is a need to earn money. Rags, kerosene, lubricants.
4. Uneven work of the hammer
Large play of the shank in the cartridge. Extraction of the bit from the axle box. Hammer pressing to the end of the tool.
5. Excessive wear and oxidation of parts
The presence of moisture and dust in the air supplied from the compressor. Removal of rust and dirt in the pneumatic sleeve. Carry out a revision of the air filter. Clean or replace as needed. Locksmith tools, keys.

Video: self-made pneumatic hammer

The choice of a jackhammer is an occupation that requires knowledge and experience. It is not superfluous to listen to the opinion of experts and masters with a lot of practical experience. But in case of a successful resolution of this issue, the mechanical assistant will serve for many years, believing and destroying any obstacles on the way.

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