Spare Part Refurbishment

Tunneling spare parts and components are usually high-quality items, available often only at relatively high cost and sometimes even only with long delivery times. Not always however it is necessary to buy new items. For costly items it makes sense to consider

Naturally we offer you full warranties on refurbished parts, sometimes even exceeding the standard warranties of new parts. This is how convinced we are of our spare part refurbishments.

Electric motors

Electric motors are expensive components that can take damage in many situations. They suffer from tunnel floodings, voltage reversals, overload or mechanical damage. In many cases, however, it is possible to refurbish the motor. The motor can be cleaned, dried and resealed after a flooding, bearings and seals can be changed, fan wheels be replaced. Depending on the size and price of the motor it is even economical to rewind the full coil package.

Tunnel Service Group GmbH is working together with a specialist company making old motors new again. Let us know what motor size and voltage we are talking about and we will give your your options.

30kW electric motor after refurbishment (75kW in the background)
Damaged electric motor 30kW
Main bearings of tunneling machines

A main bearing is potentially the most expensive part of a tunneling machine and available with long delivery times only. As long as the damage is still repairable, it makes always sense to refurbish it. Tunnel Service Group GmbH closely cooperates with one of the world market leaders in roller bearings, based in Germany. Our refurbishments comply with highest quality standards, using the same machines as new productions and come with warranties exceeding even the warranty of new bearings.

You can either send us a single bearing or have us take apart your machine front end for you. Your bearing will then be dismantled for diagnosis and come back with a detailed report on status. Based on this report we will decide together with the customer which option to choose.

In the ideal case the bearing only needs cleaning and polishing with new bolts. When the trackways are damaged they are lathed, ground and polished to remove corrosion and roller imprints in the trackways (Level II refurbishment). Together with the axial trackways the seats will be lathed down to maintain proper clearance. A Level III refurbishment means that a new set of rollers will be produced specifically for your particular bearing. This becomes necessary when either the rollers are severely damaged or when it becomes necessary to grind down the radial trackways, hence bigger roller are needed to maintain the correct radial bearing play. Finally the roller cages are cleaned and the rollers are polished by vibratory finishing. After reassembly the bearing will be conserved for safe storage.

Depending on the scope of work at your main bearing, processing time can range between two weeks up to three months when new rollers have to be produced specifically for your bearing.

Important: Do not disassemble a main bearing yourselves or pressure-wash it! This will destroy the oil layer conserving the bearing and lead to increased damage by corrosion. Simply take the bearing out, wrap it and ship it to us.

AVN800 main bearing after refurbishment and reassembly
AVN1200TC main bearing before refurbishment
AVN1200 pinions before refurbishment
seal wear rings

Seal wear rings play a vital role in protecting the expensive and central main bearing. They have to comply to narrow restrictions regarding diameter tolerances, hardness and roughness of the surface, defined by the seal requirements. This makes them a costly spare. Depending on the depth of wear, the size of nicks and thickness of potential former coatings it may be refurbished though to a state comparable to a new ring.

Tunnel Service Group GmbH has a lot of experience refurbishing seal wear rings together with a specialized partner company. The ring is first lathed or sand-blasted down to an even surface, cleaned and then coated with a flame spraying technology. Using a molybdenum compound coating we are able to even exceed the hardness requirements of the seal manufacturer and give you an even longer lifespan of your wear ring. The chamfer is then remodeled and the surface is honed down and polished to comply with the high seal requirements. Our competence from experience lies also in making sure that the edges of the coating do not break out when hit by small rocks during the drill.

Send us your seal wear rings and have us give you a quote. Depending on the workload and size of the ring you can expect a processing time from one week upwards.

AVN1200TC seal wear ring after refurbishment
AVN1200TC seal wear ring before refurbishment
Hydraulic Motors

The question if it makes sense to refurbish hydraulic motors cannot be answered in general. For small-sized hydraulic motors for Herrenknecht slurry machines up to DN1200 we always keep hydraulic motors on stock as the relatively low original prize and the high effort to refurbish the complex geometries of hydraulic motors do not allow refurbishments.

For large hydraulic motors such as the Hägglunds series, however, it can be economical to refurbish them depending on the state of wear. Especially when project constraints are pressing it may be interesting also from a time point of view.

Tunnel Service Group GmbH works together with all major manufacturers, offering high quality refurbishments including warranties. Send us your motor for a quote!

Hägglunds hydraulic motor after refurbishment
Hägglunds motor taken apart
Hydraulic Pumps

Depending on the type of hydraulic pump and state of wear it makes sense to think about refurbishment. In particular the large pumps such as Bosch-Rexroth A4V are of interest here but also small steering pumps or jacking pumps such as DYNEX or Linde pumps. Ask us for your individual hydraulic pump and we will give you our best options.

By the way - did you know that you can also refurbish your HAWE steering pump yourself? Contact us for steering pump refurbishment kits and save money.

Bosch-Rexroth A4V after refurbishment
Parker pump before refurbishment
Steering cylinders

Steering cylinders are sensitive parts; especially the lower cylinders in the machine are constantly working in a moist and muddy environment. Hydraulic and sensoric failures are the consequences.

In cooperation with the manufacturers we offer refurbishment for IMS and Montan cylinders. From a new seal set over a new sensor, magnets up to honing or even re chrome-plating of the cylinder pistons and chambers we can do whatever is necessary and economical to make the cylinders like new again. Send them to us for a quote!

By the way: We refurbish IMS boxes, too.

Defect steering cylinders before refurbishment

Your direct contact to spare part refurbishment

Harald Rütters

Harald Rütters

Spare Parts and Service

Tel: +49 (0)2421 307 57-14
Fax: +49 (0)2421 307 57-22
Mob: +49 (0)173 3579353
email: ruetters.harald[at]



An der Garnbleiche 4 · D-52349 Düren · Germany


+ 49 (0) 24 21. 307 57-0