Replacing the slip rings of the generator is a simple procedure that allows you to restore the functionality of the unit. Repairs do not require special tools or equipment. This material clearly shows how to replace the rings on a generator without breaking anything or reversing the polarity.
Signs of wear on the alternator rings
The surest sign of wear on the generator slip rings is wear on their surface. It can only be determined by visual inspection after partial disassembly of the unit. However, there are a number of indirect signs that indicate this malfunction directly during normal operation of the car.
Signs of wear on the alternator slip rings:
- the new battery is discharged;
- low onboard voltage;
- systematic undercharging of the battery;
- the battery charging lamp lights up.
All of the above problems are described in detail on the Auto without a service station website. To view these materials, please follow the appropriate links. Wear of the generator rings is not the only possible cause of the listed malfunctions. Other breakdowns are described in these materials.
Replacing generator slip rings
To replace the rings, remove the generator from the car engine. To get to the desired element, you will need to remove the brushes and diode bridges. Before you start working, your generator should be in the condition as shown in this image.
Bearing removal
The first step is to remove the bearing, which is mounted on the rotor and covers the race with slip rings. This can be done in two ways - using a special puller and improvised means. Regardless of the tool, to make the operation easier, I recommend lubricating the contact point between the bearing and the rotor shaft. Use penetrating lubricant or regular motor oil diluted with solvent.
If you have a puller, removing the bearing will not be difficult. Place the grips on the bearing and install the threaded support on the end of the shaft. When the puller handle is rotated, the bearing will first come out of place with a characteristic sound, after which it can be easily dismantled by hand.
If there are no special devices, you can use what is available in any garage. Take two sockets of the appropriate size and position them near the bearing as shown in the following image.
Next, take two flathead screwdrivers. Since some effort will be required, screwdrivers should be as strong as possible. How to remove the bearing from the alternator using these available tools is shown in the following image.
Adviсe. Make sure that the screwdrivers are opposite each other and point exactly at the center of the generator shaft. If you fail to remove the bearing on the first try, move the tools to another location and try again. Sooner or later, the bearing will be torn from its seat and then easily pulled together by hand.
Removing the skid plate
The connection points between the slip rings and the generator armature windings are covered with a protective plate. It is glued to the base. It must be removed without damage, since after replacing the generator rings it is installed back. Take a flat, sharp screwdriver, place it under the plate and lightly rip it off. To avoid breaking this part, repeat the procedure on all sides, applying measured force.
Carefully remove any remaining glue with a sharp knife. This will allow you to easily install the plate in its place after replacing the copper rings on the generator.
Disconnecting contacts
The outputs of the slip rings are soldered to the outputs of the generator rotor windings. Additionally, these places are crimped with metal plates. This complicates dismantling, since simply heating with a soldering iron will not be enough. The easiest way to cut the connection is with side cutters. This must be done carefully, and as close to the base of the slip rings as possible. The goal is to damage the terminals of the generator windings as little as possible.
Important! Don't rush to cut off both contacts. Having disconnected one of them, you must first determine which of the rings it was connected to.
In order to correctly install the contact rings during reassembly, you need to determine which ring the cut contact was connected to. To do this, use a multimeter turned on in dial mode. Check both rings in turn by applying the probe of the device to them. The second probe should touch the cut contact, and not the generator winding. Otherwise, the device will give a signal no matter which of the rings you apply the second probe to.
Having determined the desired ring, label the cut lead on the generator. In the image below this was done with a simple marker. The label can be anything. In this case, it means that the cut contact was connected to the outer (upper) ring.
Removing slip rings
To continue replacing the rings on the generator rotor, they must be removed from the shaft. To do this, use a device that is already familiar to you - heads of a suitable size and two screwdrivers.
Preparing to install new rings
The conclusions of slip rings and generator windings must be tinned with tin. This is done with a soldering iron and soldering accessories. When performing this work, it is very important to act carefully so as not to damage the rather short terminals of the generator windings.
Positioning new slip rings on the shaft
Now you need to determine the pin that matches the desired ring on the new part. To do this, use a multimeter in dial mode. You need the ring that you cut first when you removed the cage. It can be either upper or lower. Don't forget this.
Once the desired contact is found, align it with the mark you left earlier on the generator.
Installation of slip rings
All that remains is to place the correctly oriented rings in their place and solder the contacts. For shrinkage, you can use a wooden block and a light hammer. The rings need to be seated until the cage is even with the end of the rotor shaft. Aligned contacts must be soldered. For reliability, it is recommended to compress the soldering points with metal plates. They must first be tinned and given the appropriate shape.
Examination
Before returning the protective plate and bearing to their places, I recommend checking the result of the work done. The goal is to make sure that the new rings have reliable contact with the generator windings and do not short out the housing. To check the contact, turn the multimeter into continuity mode and apply the probes to the rings. The device should beep. If there is no signal, then the leads were poorly soldered.
Next, attach one probe to any of the rings, and the second to the metal part of the generator. The device should be silent. If it gives a signal, it means you made a mistake when soldering by connecting the slip rings to ground.
Installing the skid plate
The protective plate must be installed in its place. For fixation, I recommend using two-component epoxy glue. In principle, other compositions can be used. But after installation, make sure that the plate is firmly in place. To make it stick better, press it down for a while with a weight. This could be a tube or a head from a set of wrenches on which something heavy is placed.
Bearing installation
This is the last step in replacing the alternator slip rings. To install the bearing onto the rotor shaft, use a suitable size mandrel and an impact tool. Do not overdo it, as you risk damaging the bearing itself, the rings, and the protective plate.
Conclusion
Replacing rings is one of the types of generator repairs that is performed when parts wear out. It does not require special tools and equipment. It is enough that there is in almost any garage of a motorist. After final assembly and installation of the generator, be sure to check its operation. This can be done using a multimeter (measuring the voltage at the battery terminals) or an on-board voltmeter.
