LTN Servotechnik

Manufacturer information and published contact details

LTN Servotechnik contact details

Former head office and production (operations ceased 30 April 2026)

Georg-Hardt-Straße 4
83624 Otterfing
Germany

Website heidenhain.com/about-us/strong-brands-for-your-application/ltn

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Contact details as published by HEIDENHAIN Corporate Group (LTN brand; LTN Servotechnik GmbH ceased operations 30 April 2026), checked 2026-10-30. Specify Motion is not affiliated with HEIDENHAIN Corporate Group (LTN brand; LTN Servotechnik GmbH ceased operations 30 April 2026).

LTN Servotechnik product lines

Who LTN Servotechnik was

LTN Servotechnik GmbH was a German manufacturer of resolvers and slip rings, based in Otterfing in Upper Bavaria and part of the HEIDENHAIN group. According to HEIDENHAIN, the company ceased operations on 30 April 2026. The LTN name continues as a HEIDENHAIN brand for resolvers, while LTN slip rings have been discontinued.

For engineers this matters in two ways. If you run servo motors with LTN resolvers, supply continues through HEIDENHAIN. If you maintain machines with LTN slip rings, such as packaging machines, wind turbines or medical lamps, you will need a spares strategy or a specified equivalent.

History and ownership

LTN’s 2019 company brochure describes its development:

• 1979: the company is founded in Munich, making rotary encoders, potentiometers and slip rings.
• It later moves into production of resolvers, slip rings and encoders, ships its first slip rings for wind turbines, adds video and later HD image transmission across slip rings, supplies slip rings for medical lamps and starts brushless resolver production.
• The business moves to Otterfing, south of Munich, onto a 4,400 m² site, later enlarged to 6,500 m² with a new production hall and warehouse. In 2015 it is named the local region’s business of the year.
• By 2019 the brochure describes a team of about 250 people, with its registered office in Otterfing (Munich register HRB 121158).

In 2017 HEIDENHAIN Corporation, which held exclusive North American distribution rights, launched the LTN SR/SH085 slip ring family. HEIDENHAIN now presents LTN as one of its group brands, but its pages do not say when LTN joined the group. Deublin, the rotary union maker, states that it acquired select LTN Servotechnik slip ring models.

Product portfolio

Our series records cover both product families:

• Frameless resolvers: brushless kit resolvers in 36.83, 50.77 and 71.02 mm outside diameters, with 1 to 5 pole pairs, 6 to 10 arcmin accuracy, up to 20,000 rpm and -55 to +155 °C. HEIDENHAIN now produces and sells these.
• Housed resolvers: brushless resolvers in their own housing, giving absolute position within one revolution, with customised versions on request. HEIDENHAIN lists the variants on its corporate site.
• SR/SH085 slip rings: a compact family with up to 16 poles for power and data, designed for vibration and shock and aimed at packaging and side-sealing machines. Discontinued.
• LTN slip rings: standard and custom rings that carried signals from a few mV or mA up to 300 A and 1,500 V, Fast, Gigabit and 10 Gigabit Ethernet certified to TIA-568 and EN 50173, and real-time fieldbuses, plus contactless fibre optic joints. Discontinued.

LTN also supplied evaluation electronics for its resolvers, including encoder-output emulation and digitisation of the analogue signal.

Technologies and standards

A resolver is a rotary transformer: the rotor angle modulates two output voltages (sine and cosine), and brushless designs pass the excitation to the rotor inductively. That makes resolvers wear-free and tolerant of heat, shock and contamination, and they give absolute position within one turn without recalibration at power-up. They are a common choice for servo motor commutation in harsh environments. Our guide to absolute vs incremental encoders and the encoders hub explain where resolvers fit against optical and magnetic feedback.

On slip rings, LTN’s distinguishing claims were high data rates up to 10 Gigabit Ethernet with recognised cabling certifications, video transmission and resistance to salty air and severe vibration. For replacing a discontinued ring, see Ethernet through slip rings and how to specify a slip ring.

Industries served

LTN and HEIDENHAIN name machine tools, packaging machines, industrial robots and heavy machinery for resolvers. LTN’s slip rings served wind turbines, medical lamps and imaging, packaging and side-sealing machines and video systems. See slip rings for wind turbines and slip rings for packaging.

Points to check when replacing LTN parts

For resolvers, match pole pairs, transformation ratio, excitation voltage and frequency, phase shift and the mechanical envelope, because the servo drive is set up for a specific resolver. Frameless sizes are quoted to two decimal places for a reason: the stator must fit the existing housing bore. For slip rings, confirm whether Deublin now supplies the model you have before redesigning, and if not, record the current, voltage, data rate, bore, speed and connector details of the existing ring before it leaves the machine.

Global and UK presence

With LTN Servotechnik GmbH closed, resolver sales and service run through HEIDENHAIN’s worldwide sales and service organisation, so UK engineers should contact their local HEIDENHAIN office. HEIDENHAIN’s US site gives +1 847 490 1191 for North American product questions. Slip ring warranty claims use the online form on HEIDENHAIN’s LTN page. We have not listed the former Otterfing telephone numbers because the company is no longer operating.

What to send when replacing an LTN slip ring

Give the LTN part number and label details, number of circuits with current and voltage for each, any Ethernet or fieldbus channels and data rate, bore and envelope, speed, environment and mounting. Photographs and a drawing of the installation help an engineer match an equivalent.

Specify Motion is independent of LTN and HEIDENHAIN. Our engineers can help source LTN resolvers or propose equivalents for discontinued LTN slip rings from our supply network on published figures; see find a replacement or the slip rings hub.

LTN Servotechnik history: key dates

1. 1979Founded in Munich, making rotary encoders, potentiometers and slip rings
2. 2015Named the local region's business of the year (company brochure)
3. 2017HEIDENHAIN Corporation launches the LTN SR/SH085 slip ring family in North America
4. 2026LTN Servotechnik GmbH ceases operations on 30 April; HEIDENHAIN continues LTN resolvers

LTN Servotechnik encoders

Inductive encoder

LTN frameless resolvers

Brushless frameless (kit) resolvers in 36.83, 50.77 and 71.02 mm outside diameters with 1 to 5 pole pairs, 6 to 10 arcmin accuracy, up to 20,000 rpm and -55 to +155 °C, now produced and sold by HEIDENHAIN.

Inductive encoder

LTN housed resolvers

Brushless housed resolvers giving an absolute position within one revolution, wear-free for harsh environments, with customised versions on request; continued by HEIDENHAIN.

LTN Servotechnik slip rings

Slip rings · discontinued

SR/SH085 slip rings

Compact slip ring family with up to 16 poles for power and data, built for vibration and shock with high-speed options, aimed at packaging and side-sealing machines.

Slip rings · discontinued

LTN slip rings (power, signal and Ethernet)

LTN's custom and standard slip ring range carried signals from a few mV or mA up to 300 A and 1,500 V, Fast, Gigabit and 10 Gigabit Ethernet, real-time fieldbuses and contactless fibre optic channels.