How To Properly Repair A Hitachi Grinder With Your Own Hands

2023 Author: Philip Bishop | [email protected]. Last modified: 2023-08-25 07:54

• Construction features of Hitachi grinders
• Hitachi grinder repair tool
• Electrical malfunctions Hitachi grinder
• Checking the electric motor
• Mechanical malfunction of the Hitachi grinder
• Hitachi grinder gearbox repair
• Hitachi G13SR3 grinder reducer design with disc up to 125
• How to remove the driven gear from the gearbox shaft of the Hitachi grinder with a disc up to 125
• How to remove the drive gear from the rotor shaft of the Hitachi grinder with 125 disc
• Replacement of bevel gears in Hitachi grinders
• The design of the reducer grinder Hitachi G23SCY with a disk up to 230
• How to remove the driven gear from the gearbox shaft of the Hitachi grinder with a disc up to 230
• Lubrication rules for Hitachi grinders
• Hitachi grinders repair video

Hitachi grinders are especially popular among Russian builders. There are two reasons: a high degree of reliability and the absence of counterfeits. In addition, the Japanese brand, founded in 1910, has an affordable price, a lot of innovation, and high reliability.

Angle grinders (grinders) from Hitachi are available in several varieties, depending on the power.

The purpose of this article is to propose do-it-yourself repair methods for Hitachi grinders. Repair of Hitachi lugs, as a rule, is carried out under warranty at service centers. But after reading the proposed instructions, you can easily repair the Hitachi grinder.

Construction features of Hitachi grinders

Even in appearance, you can immediately say that this is a Hitachi grinder. The upper plastic case of Hitachi lugs consists of two parts of different colors and has lining of the original form.

External contours of the grinder's body parts, a special bright green-black color, an additional handle with mandatory model marking, a bright white inscription - these are the main differences in the appearance of the Hitachi grinder.

Several models of grinders are produced under the Hitachi brand. We will highlight the most popular ones: G13SE2, G13SR3, G23SEY, G23SRU.

The numbers in the designation indicate the maximum diameter of the cut-off wheel used.

Hitachi grinders, marked with the number 13, have a power of up to 1000 watts. The grinders with numbers 13 are designed for small work with a circle of 125.

The grinders with numbers 23 have a power of more than 1000 watts. The grinders with the designation 23 use 230 discs and can perform more complex work.

The design feature of Hitachi grinders is the presence of overheating protection and an advanced cooling system.

All Hitachi grinders are equipped with an additional handle.

Structurally, the grinders of the Hitachi family do not differ from each other. Although minor changes may occur.

Hitachi grinder repair tool

It is impossible to repair a Hitachi grinder without a tool. You must prepare a set of screwdrivers, a device for testing short-circuited turns in windings, a tester, pliers, open-end wrenches. You cannot do without improvised devices if you want to repair the Hitachi grinder with your own hands.

It is good if you have a screwdriver and interchangeable screwdriver bits, correctly selected according to the slots of the screws being unscrewed.

Of the accessories you will need: a bearing puller, a press, a vice, soft metal accessories.

Pullers are needed to remove gears and bearings. It is convenient to clamp individual grinder units in a vice. Open-end wrenches unscrew the drive pinion fixing nuts.

When carrying out repairs, you cannot do without lubricants, removers, paint.

For wiping, you will need a rag or chunks of clean material.

Don't forget to equip your workplace correctly. It should be well lit.

All Hitachi grinder malfunctions can be divided into two types: electrical malfunctions and mechanical malfunctions.

Electrical malfunctions Hitachi grinder

Hitachi grinders suffer from breakdowns of switches, carbon brushes, a broken wire of the stator windings.

As with all electrical tools, the appearance of the health of the electrical part largely depends on the condition of the carbon brushes. In the Hitachi grinders, carbon brushes are installed with a built-in device, popularly called a "shot". The task of such a device is to prevent the inclusion of Hitachi grinders with a high degree of wear of the carbon brushes.

A weak point in the design of the electrical part of Hitachi grinders is the place where the power cable is inserted. In this place, most often there is a break, break, bare cable.

Checking the electric motor

Several points indicate the malfunctioning of the grinder:

• Rotation of the working body in jerks;
• Drop in revolutions and power of the Hitachi grinder;
• Spontaneous set of revolutions;
• Strong heating of the stator housing;
• Significant sparking in the collector area;
• The appearance of a burning smell, smoke.

A drop in power from the power tool is associated with an open or short circuit in the rotor windings.

Rotor repair

Repairing the rotor of the Hitachi grinder is no different from the repair of the rotor of any grinder. Not every consumer can fix this kind of malfunction. To do this, you need to have not only special devices, but also the skills of a winder. It is preferable to send the failed rotor to specialized service centers.

But for those who like to get to the bottom of the truth, we recommend that you familiarize yourself with the rotor rewinding algorithm.

A rotor failure is indicated by the appearance of burning in the collector area. As a rule, lamellas burn out, a dark coating appears on the winding wires.

The rotor must be removed from the housing:

• Remove carbon brushes;
• Remove the gearbox cover;
• Unscrew the pinion nut;
• Pull the rotor out of the gearbox housing;
• Pull the rotor out of the stator housing.

If there is an IK-2 device, then it is possible, without disassembling the rotor, to measure the presence of a short circuit of turns or an open winding.

Disassembly of a failed rotor begins with dismantling the rotor bearings and impeller from the armature shaft. It is recommended to remove the bearings and impeller with special pullers so as not to damage the parts. If the collector is damaged and cannot be restored, it must also be dismantled using a puller. Pre-unsolder the ends of the windings soldered to the collector lamellas. It remains to remove the burnt-out winding. Having cut off the end of the winding with a hacksaw, count the number of turns in several slots, sketch the direction of winding, determine the percentage of filling the slots of the armature core. Use a micrometer to measure the diameter of the wire you are using. You will need this data if you decide to wind the Hitachi grinder anchor with your own hands.

For other consumers, we recommend purchasing a new rotor in service centers or in online stores.

Stator repair

The failure of the stator is most often indicated by a significant overheating of the grinder's body and a spontaneous set of revolutions that cannot be controlled. The fault can be determined by pulling the stator out of the housing:

• Disconnect the gearbox housing and stator housing by unscrewing the four screws;
• Pull the gearbox with the rotor out of the stator housing;
• Pull out the plastic stator protection;
• Unscrew the two screws securing the stator and pull it out.

A stator break is easily detected by a tester. But the turn-to-turn short circuit is best measured with an IK-2 device or an oscilloscope. DIY Hitachi grinder stator repair can be done at home. But you need to have some skills.

The failed stator is first disassembled:

• Outgoing contacts are released;
• From one end of the core, the winding is cut off with a hacksaw for metal;
• The number of laid turns of wire, the direction of winding, the percentage of filling the grooves are considered;
• The diameter of the wire used is measured with a micrometer;
• The core is cleaned from traces of carbon deposits, drops of molten copper wire.

The manufacture of the stator is described in detail on the pages of our website. For those who wish, it will not be difficult to complete this work.

A few helpful tips when winding:

• Use a wire of the same diameter as was used in the stator;
• If the volume of the stator slots allows, it is preferable to use a wire of a larger cross-section, but do not overdo it;
• Try to stack the turns tightly when winding, controlling the shape of the winding;
• Tie the winding carefully with a mounting thread or cord;
• Be sure to impregnate the winding of the wound stator with paint or varnish, using an alternating voltage through the LATR during impregnation;
• At the end of winding, clean the middle of the stator core from traces of paint and varnish.

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Repair of electrical control circuits of Hitachi grinders

The electrical control circuits of the power tool are of a simple design. They perform the task of smoothly starting the tool, possibly adjusting the speed, turning the tool on and off. The control circuits include a switch, a speed controller, an electric motor, carbon brushes, a supply cable and switching elements. Let's consider the work of the electrical part of the Hitachi grinder using the example of two models: Hitachi G13SB3 and Hitachi G23SCY.

Electric diagram grinder Hitachi G13SB3 lgm 125

Power is supplied through the cable pos. 52 to the terminals pos. 53, which are connected to the switch pos. 42. At the entrance to the Bulgarian body, the cable is fixed with a clamp, pos. 55. A noise suppressor pos. 46 and wires to the carbon brushes pos. 39 are connected to the switch. Hitachi grinders use hitchhiking carbon brushes. The size of the carbon brushes in the Hitachi G13SR3 grinder is 6.5 × 7.5 mm. Carbon brushes are installed in the brush holder pos. 38. Turning on the Hitachi grinder occurs by moving the switch button pos. 36.

The most frequent malfunctions in Hitachi grinders occur when the supply cable fails at the entry point, the carbon brushes are worn out, pos. 39, and the switch pos. 42 fails.

This kind of malfunction is eliminated by replacing a failed part or a piece of wire.

Mechanical malfunction of the Hitachi grinder

In Hitachi grinders, the reliability of the gearboxes is admirable. But this is with proper operation.

In case of overheating or periodic jamming of the tool, if dust gets in, or untimely replacement of carbon brushes, no grinder will last long.

A large driven gear in Hitachi grinders with a disc up to 125 mm is attached using a keyway. For grinders with a disc up to 230 mm, the gear is pressed onto the spindle shaft. The small drive gear in any Hitachi grinder design is fastened with a key and fixed with a nut.

Hitachi grinder gearbox repair

The Hitachi grinder gearbox is manufactured with high precision. In the LBM there is practically no beating of the gear wheel teeth. Gear wear is particularly affected by improper use. Consider the repair of Hitachi grinder gearboxes on two models: Hitachi G13SR3 and Hitachi G23SCY.

Hitachi G13SR3 grinder reducer design with disc up to 125

In grinders with a disc diameter of up to 125 mm, the driven gear pos. 33 is attached to the spindle shaft, pos. 26, using a keyed connection, pos. 25. The accuracy of the keyway connection excludes the formation of play of the driven gear on the shaft. The presence or absence of backlash can be determined by rotating the spindle shaft in different directions. If there is a large backlash, both gears must be replaced at the same time, since they are made in pairs.

How to remove the driven gear from the gearbox shaft of the Hitachi grinder with a disc up to 125

The driven gear shaft is disassembled in the following sequence:

• Unscrew 4 (four) screws M4 × 12 pos. 24;
• The cover is removed pos. 23 with the shaft;
• The retaining ring, pos. 15, and the ring for the shaft, pos. 17, are dismantled;
• The shaft is pressed out (knocked out) from the cover, into which the bearing, pos. 21, is mounted. Bearing type 6021DD;
• The driven gear pos. 33 is removed from the shaft by simply tapping on the shaft;
• The key is removed pos. 25

To get the bearing pos. 21, it is necessary to unscrew 2 screws M4 × 10 pos. 19, fixing the bearing cover pos. 20. The Hitachi G13SR3 grinder uses three types of bearings: 628 - mounted on the gearbox spindle, 626 - mounted on the rotor from the drive gear side, 6201 - mounted on the rotor from the collector side.

How to remove the drive gear from the rotor shaft of the Hitachi grinder with 125 disc

To remove the drive gear pos. 33, it is necessary to clamp the rotor, pos. 8. The gear is fixed with an M6 nut pos. 4. Using an open-end wrench, unscrew the nut by turning counterclockwise. After removing the gear, remove the rotor from the gear housing.

Replacement of bevel gears in Hitachi grinders

In Hitachi grinders, broken bevel gears are replaced in pairs. To replace gears leads to wear of the teeth, licking, destruction of several teeth.

The design of the reducer grinder Hitachi G23SCY with a disk up to 230

Reducer grinders with a disc up to 230 mm is much more powerful. In the design of the reducer 230, the clutch item 24 and the damper item 23 are used. This design plays the role of a clutch, preventing shock when the working disc is biting or emergency stopping. The clutch allows the grinder to start smoothly.

How to remove the driven gear from the gearbox shaft of the Hitachi grinder with a disc up to 230

To dismantle the gears of the reducer with a disc up to 230, you should resort to making sure that no restoration work is possible.

Disassembly of the driven gear assembly is no different from a similar disassembly of the grinder assembly with a disc up to 125 mm. The only difference is that in the grinder 230 the gear wheel pos. 20 is pressed onto the shaft pos. 29. It is better to remove the gear from the shaft using a press, but improvised means will do. For example, a vice. The shaft is installed in the bearing pos. 27. Bearing type 6302DD.

Three types of bearings are used in the Hitachi G23SCY grinder: 6302DD - mounted on the gearbox spindle, 6301DD - mounted on the rotor from the side of the pinion gear, 6000VV - mounted on the rotor from the collector side.

Lubrication rules for Hitachi grinders

By the quality of the lubricant in the gearbox, you can determine the percentage of wear of the bevel gears. The darker the lubricant, the more traces of metal shavings in it, the greater the likelihood of an increased percentage of gear wear. The percentage of wear on the gears of the reducer is easily determined by the contact patch.

Use a special flushing fluid to remove old grease. To thoroughly remove all old grease, it is recommended to warm up the gear housing with a hair dryer until the grease turns into a liquid.

New grease is applied to the gear housing in an amount that takes up less than half of the housing volume. Manufacturers produce their own grease for lubricating gearboxes. But Russian manufacturers have learned how to make lubricants that are not inferior in quality to foreign ones, but whose price is much lower.

Conclusion:

• the reliability of Hitachi grinders is ensured by technological and organizational measures;
• Hitachi grinders are hard to counterfeit;
• in Hitachi grinders, the basic principle is implemented, the best ratio of price and quality;
• you can prolong the work of the grinder by timely changing the carbon brushes, changing the lubricant, and gentle operating modes.

Hitachi grinders repair video

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