Do-it-yourself Repair Of The Hitachi DH24 Perforator And Video

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

Malfunctions of the mechanical part of the Hitachi DH24PC3 rotary hammer
Faults in which the hammer drill drills but does not hammer
Drunken bearing and clutch repair or replacement
Repair or replacement of the piston sleeve
Repair of striking mechanism strikers
Intermediate shaft clutch repair
Replacing rubber O-rings
Malfunctions in which the hammer hammer chisels, but does not drill
Inspecting the gear on the intermediate shaft
Repair of the gear shaft of the barrel of the percussion mechanism
Electrical faults
Faults in which the hammer drill does not drill or chisel
Inspection of the electrical part of the control
Hitachi perforator repair video

At first glance, repairing a Hitachi DH24 rotary hammer with your own hands may seem difficult, but having familiarized yourself with the drill diagram and instructions for disassembling the Hitachi DH24PC3 hammer drill. The only requirement is to disassemble and assemble the rock drill in a specific sequence.

Structurally, the Hitachi perforator is made according to the block scheme. The tool includes a mechanical block, a stator block and a control circuit block.

Malfunctions of the mechanical part of the Hitachi DH24PC3 rotary hammer

Hitachi rotary hammers are a reliable tool, easy to use, in high demand among professionals and among Russian craftsmen and DIY enthusiasts.

But any tool in use over time requires maintenance, periodic inspection and, if necessary, repair.

Any hammer drill has three main types of faults:

malfunctions in which the hammer drill drills, but does not hammer;
malfunctions in which the hammer drill hammers but does not drill;
malfunctions in which the hammer drill does not hammer and drill.

Faults in which the hammer drill drills but does not hammer

The drilling process in Hitachi rotary hammers is provided by transmitting torque from the rotor through the intermediate shaft to the hammer barrel.

The chiseling process is provided by converting the rotational moment of the intermediate shaft into a reciprocating one through a rolling bearing, popularly called "drunk bearing".

The shock impulse is created by moving the strikers in the piston sleeve and the barrel of the striking mechanism. A drunken bearing attached to the intermediate shaft axis converts rotary motion into reciprocating motion.

The reasons why a hammer drill can drill, but does not hammer, may be:

the destruction of a drunk bearing;
destruction of the barrel piston sleeve;
jamming or destruction of strikers;
turning the clutch in a drunk bearing;
wear of rubber sealing rings.

When a drunk bearing is destroyed, it becomes impossible to convert the torque into a reciprocating impulse. But at the same time, rotation is transmitted to the barrel due to gears. More complete instructions for disassembling the Hitachi puncher.

Drunken bearing and clutch repair or replacement

Drunken bearing failure occurs when the integral bearing race is destroyed. Such a malfunction is eliminated only by a complete replacement of the drunk bearing. The Hitachi DH24PC3 hammer drill has a bearing article 324533. There is no Russian analogue for this bearing, but Chinese-made bearings are produced, which are of good quality.

To replace the rolling bearing, it is necessary to remove the intermediate shaft from the inner housing of the rock drill.

Dismantling the drunk bearing is carried out in conjunction with the clutch. The destroyed drunk bearing pos. 53 cannot be restored, but the clutch clutch pos. 52 with slight wear of the engagement splines can be restored.

Repair or replacement of the piston sleeve

The piston liner of the Hitachi DH24PC3 hammer drill

Loss of impact can occur when the piston liner is destroyed, pos. 39. The piston liner may fall off the ears of the piston pin fastening pos. 42. At the piston liner, the skirt, the thin part of the piston, is destroyed. There are cases that the striker of the percussion mechanism pos. 37 bites into the sleeve.

When parts of the piston sleeve are destroyed, it is completely replaced. It is almost impossible to repair the piston sleeve.

Repair of striking mechanism strikers

In the barrel of the percussion mechanism, two types of strikers are used. Striker poz.37 of the cylinder liner of the percussion mechanism and the striker of the barrel poz.29.

On the striker, pos. 37, a rubber ring, pos. 38, and on the firing pin, pos. 29, a rubber ring, pos. 30, is mounted. and a rubber gland pos. 32.

In addition, on the firing pin, pos. 29, the holder of the impact mechanism, pos. 31, is installed, on both sides of which O-rings, pos. 30, 32, are installed. Then, the damper holder, pos. 35, is mounted on the firing pin, which is fixed with the retaining ring, pos. 36. Item 34 is a rubber gasket.

The main breakdown of the strikers is their wear, wear of the O-rings during shock loads. The striker can bend, flatten.

Breakdowns of this kind are eliminated by replacing the parts of the percussion mechanism and the obligatory replacement of all rubber sealing rings.

To purchase new spare parts, you need to know the part numbers of the ordered parts, which are indicated in the photographs shown.

Intermediate shaft clutch repair

When using the punch in the “Impact” mode, do not try to press hard on the tool.

The loss of the shock pulse leads to slipping of the clutch, pos. 51, on the intermediate shaft, pos. 52.

The teeth of the clutch lick during hard work. This occurs when the pressure on the working tool is increased during work or the pressure of the spring (pos. 50) on the clutch is weakened.

The tooth profile can be restored using a file. If the tooth is not too licked, then with a round file the tooth profile is corrected by restoring its corners on the clutch and on the intermediate shaft pos. 52. Otherwise, it should be replaced with severe wear.

Replacing rubber O-rings

Several O-rings are used in the shock impulse chain.

The loss of the shock impulse on the working element occurs due to abrasion of the O-rings. The malfunction manifests itself gradually, as the seals wear out.

Malfunctions in which the hammer hammer chisels, but does not drill

Chiseling of the Hitachi DH24PC3 rock drill occurs by transferring the reciprocating motion from the intermediate shaft through the rolling bearing to the cylinder moving in the barrel of the percussion mechanism. Two strikers are installed in the perforator cylinder. This is the movement of the striker and produces the transfer of the shock impulse to the table, in the keyless chuck of which a working tool is inserted, for example, a drill.

The drilling process in the Hitachi DH24 hammer drills is provided by the transfer of torque from the rotor, through the intermediate shaft to the hammer barrel. A keyless chuck is fixed at the end of the barrel, into which the working tool is installed.

The helical gear wheel of the rotor, pos.62, transmits the torque to the helical gear of the larger diameter, pos. 54, fixed on the intermediate shaft, pos. 51. The rotating intermediate shaft transmits with its small spur gear the torque to the large spur gear pos. 25, fixed on the barrel of the percussion mechanism.

Drilling in the Hitachi DH24 hammer drill occurs due to the rotation of the keyless chuck, in which the drill or drill is fixed.

This kind of malfunction results in:

- turning the gear pos. 49 on the intermediate shaft pos. 52;
- turning the gear, pos. 25, on the shaft of the barrel, pos. 24.

Inspecting the gear on the intermediate shaft

The gear wheel pos. 49 can turn on the intermediate shaft pos. 52 due to the weakening of the pressing force of the spring pos. 50 and the incorrect operation of the mode switch pos. 48.

This malfunction of the Hitachi Punch is eliminated by restoring the splines on the gear 5 and the shaft.

The splines can be restored with minor wear by correcting the spline tooth shape. To do this, it is necessary to correct the contours of the tooth using a round file, clamped in the drill chuck.

The operation of the mode switch 4 can only be restored by completely replacing it.

Repair of the gear shaft of the barrel of the percussion mechanism

The gear wheel pos. 25 is installed on the table shaft and is fastened there by means of the spring pos. 26, fixed with the retaining ring pos. 28 and the steel washer M30 pos. 27.

When the spring force is weakened, pos. 26, the gear jumps out of engagement and turns.

A malfunction of this kind is eliminated by replacing the spring and correcting the shape of the teeth of the engagement.

Electrical faults

If a malfunction occurs in the electrical part of the hammer drill, the tool stops working completely.

Faults in which the hammer drill does not drill or chisel

The reasons why the rock drill stops working include:

destruction of the teeth of the small helical gear of the rotor;
failure of the rotor;
short circuit or open circuit in the stator circuits;
open or short circuit in control circuits.

Rotor repair

With a slight wear of the helical gear, the malfunction is eliminated by restoring the shape of the tooth, if possible. Otherwise, the gearbox must be replaced completely.

In the event of a short circuit or breakage of the rotor windings, failure of the collector lamellas, the gearbox can be repaired by hand or replaced with a new one. The new one is quite expensive. And not everyone can make a rotor with their own hands. The choice is yours. You can read more about how to repair a rotor with your own hands in our articles.

Stator repair

The stator is repaired if a short circuit or breakage is found in it. It is not difficult to repair the stator if you know the number of turns, the cross-section of the wire and its brand.

If your stator burns out, or a break is found in it, then when disassembling it, count the number of turns and measure the cross section with a micrometer. Pay attention to the percentage of filling the stator slots with the winding. With an insignificant percentage of filling, the diameter of the winding wire can be increased.

Inspection of the electrical part of the control

Of the faults in the control circuits, they most often manifest themselves in a break in the power wire at the point of entry into the instrument and the failure of the start button.

Hitachi DH24PC3 rotary hammer control circuit diagram

The tool uses a combination switch to start the hammer drill and adjust the speed. The hammer drill uses a push-button switch 220 V (OLD 331454/324536).

Carbon brushes of Hitachi DH23PC3 rotary hammer

Carbon brushes pos. 74, 77 are fixed in special holders pos. 75. The reason for the short circuit of the control circuits can be the throttle pos. 69 and the diode contact pos. 72. It is important to monitor the size of the brushes and replace them in time.

The article lists the main types of malfunctions in Hitachi DH24PC3 rotary hammers. If you have encountered other problems or know how to fix them, write to us.