Crankshafts

We offer comprehensive rebuilding of crankshafts. Our specialist knowledge and technical facilities allow us to carry out the entire shaft rebuilding process. Our works include: hardfacing, grinding, polishing and dynamic balancing. Each rebuild ends with control measurements, so that the customer can be sure that they receive an operational crankshaft after the work is complete.

Crankshaft damage is a failure that can be caused by improper installation or insufficient lubrication. Any defect in this part requires immediate repair, as the crankshaft is a key component in an engine: the crankshaft allows the reciprocating motion of the pistons to be converted into a rotational motion, which is then transmitted to the wheels. These parts work under enormous load. If they are damaged, the vehicle can no longer be driven effectively. In this case, it is necessary to rebuild the crankshafts, and the crucial element is the rebuilding of the journals. During the repair, they are ground, polished, balanced and, if necessary, also hardfaced. The purpose of these operations is to improve the quality of their surface, fill any defects, and reduce vibrations.

The crankshaft is a part of the engine that works under great load, which exposes it to various types of damage. As a result of engine operation or shaft seizure, numerous irregularities may be formed on its surface, which cause the oil to be spread unevenly over the surface. This can lead to problems, as the oil film is unable to be maintained properly on the surface, which causes much faster wear of the shaft. The bearing surface can also be welded, and in extreme cases they can even break. In this situation, the only effective way to repair these elements is to regrind the surfaces.

Therefore, Crankshaft grinding is used when the shaft dimensions are not in accordance with the manufacturer’s standard, either due to engine wear or shaft seizure. We can restore the crankshaft by grinding the surfaces of the crankpins and journals to the required dimensions. However, before we do this, the shaft has to be thoroughly cleaned and then checked that it is not bent or cracked. Then the shaft is placed in a specialised grinder intended for crankshaft grinding. During grinding, the shaft journals are aligned until their dimensions are as specified by the manufacturer. This allows us to maintain the play between the bearings, connecting rod and shaft. In this way, the friction forces can be distributed over the largest possible surface area.

After grinding, the crankshaft journals are additionally polished to improve the quality of their surface so that they work with the bearing surfaces better. This reduces the resistance of shaft rotation, extending the service life of the bearings as well as the shaft itself.

We provide crankshaft grinding services using the services of a Danish company, AMC-Schou, and an Italian company, Robbi. We are able to grind shafts up to 1,700 mm in length.

Crankshaft balancing is the last operation performed on the crankshaft during the rebuilding process. Thanks to the Sunnen dynamic balancing machine, we can precisely balance straight and V-shaped shafts. Comprehensive crankshaft balancing involves aligning the complete pistons and connecting rods and balancing the flywheel, balancing the shaft and finally balancing the shaft with the flywheel. Crankshaft balancing is a very important part of shaft repair. It has the following advantages:

• reduces engine vibrations,
• extends the service life of the components,
• increases engine power,
• reduces fuel consumption.

In the event of crankshaft wear beyond the catalogue dimensions, we offer the reconstruction of damaged journals by hardfacing. We perform crankshaft hardfacing using an automatic welding machine from Rege, a German company. This technology allows us to achieve the desired technical parameters of the journals subject to hardfacing.

The crankshafts hardfacing process uses welding techniques to apply a metal layer to the crankshaft surface. Any defects on the crankshaft resulting from intensive use or unexpected failures are filled with a material of appropriate hardness. Hardfacing is an excellent way to reconstruct the surface finish of crankshafts and restore them to their factory parameters. It can make the service life of crankshafts up to three times longer. For this reason, it is an integral part of engine rebuilding, making it possible to restore the full efficiency of the shaft and eliminate any signs of wear and tear. Hardfacing can be used on crankshafts of engines in many types of vehicles: cars, trucks, tractors, motorcycles, heavy construction machinery, ATVs and scooters.