Autotractor is a term for a family of modern, rugged watch movements from Jaeger-LeCoultre. Due to the numbering of the calibres in this family, it is also often referred to as the "970" family or by the calibre number of the most widely-used variant, Calibre 975.
As Jaeger-LeCoultre was recovering from the quartz crisis and a series of ownership changes, the company decided to begin investing in movement technology. The high-profile Hybris Mechanica series brought renewed respect and interest in the company, but it was mainstream watch movement technology that would keep the company in business. Beginning in 1996, the company tasked a team, led by R&D Director Jean-Claude Meylan, to produce a new basic automatic movement with the following characteristics: Reliable, durable, accurate, easy to maintain, service and regulate and relatively maintenance free. Eight years later, in 2004, the Autotractor was launched.
Introduced in 2004, the "Autotractor" family was designed to bring modern developments to market in a new family of high-end watch movements. Among the main advancements found throughout this family of movements are the following:
- Ceramic bearings, zirconium-oxide coated in steel, reduce maintenance requirements
- Unidirectional (counter-clockwise) winding produces more power in real-world use than bi-directional systems
- A "SPYR" design for the gear teeth is more rounded to reduce friction and maintain more even torque (as used in the JLC Mechaquartz)
- A large, free-sprung balance wheel
- Laser-welded hairspring with adjustment by means of screws on the periphery of the balance
- A screwed cross-over bridge rather than a balance cock for durability and shock resistance
- "Maltese cross" date changing gear allows instantaneous and bi-directional movement of the date wheel
- An in-house mainspring manufactured by A. Lange & Söhne
- A small seconds design with the center wheel in the middle, as in traditional watches
Note that two Autotractor movements, Calibre 976 and Calibre 986, are hand-winding rather than automatic but retain most other features of the family and are generally considered Autotractor movements.
Autotractor Family Calibres
The first Autotractor movement was Calibre 975, and it has spawned a family of movements that share a similar design:
- Calibre 751 - Chronograph
- Calibre 752 - Chronograph world timer
- Calibre 970 - Grande Reverso Automatic GMT/big Date
- Calibre 971 - Ladies GMT
- Calibre 972 - Minute counter
- Calibre 975 - Dual timezone
- Calibre 976 - Grande Reverso 976 manual winding
- Calibre 977 - Reverso Squadra Hometime GMT/small date
- Calibre 979 - Depth gauge
- Calibre 986 - Grande Reverso 986 Duodate manual winding GMT/date
Many of the innovations found in the Autotractor family itself have spread to other contemporary movements from Jaeger-LeCoultre. These are often referred to as being "Autotractorized" and this has led to some confusion regarding their relationship to Cal. 975 and the rest.
The following Calibres feature some elements of the Autotractor design, although they are not part of this family of movements:
- Calibre 899 (and similar 896 and 898) are descendants of Calibre 889 but feature ceramic bearings and SPYR gears
- Calibre 925 has unidirectional winding
- Calibre 938 has ceramic bearings and a free-sprung balance along with Jaeger-LeCoultre's signature Réserve de Marche complication
- Calibre 956 (and related 912) has ceramic bearings and SPYR gears
- Calibre 978 has ceramic bearings, SPYR gears, and a similar balance to the Autotractor