The traction motor is installed between the wheels of a wheel set in the bogie or chassis of the traction vehicle . A tubular bearing is attached to the cylindrical motor housing and encloses part of the wheelset shaft . The power is transmitted via a pair of gears, with a small pinion on the motor shaft and a large gear on the axle shaft.
The engine is supported on the other side on the bogie or on the vehicle frame. In the past, this support was provided by a nose cast onto the motor housing, which is why this type of drive is referred to in English as nose-suspended . A suspension is usually integrated into the support.
In rare cases the torque support is on the bracket tube opposite the drive motor. Such a version was used on CD 181/182 . There two support arms run away from the motor in a radial direction from the bearing tube and finally with a lateral kink in a spring-loaded receptacle in the bogie. Here the arms can support the deflected motor weight, but also the reaction to the drive torque . Horizontal play towards the sides of the vehicle and lengthways protect these retaining arms from the significantly greater forces that the wheelset is only supposed to exert on the bogie via its axle bearings.
The cradle bearing drive is the simplest way of suspending traction motors in the bogie. It is an inexpensive drive and was the classic drive type for trams and electric locomotives until 1950 . It is still the most commonly used drive and is still used in slower vehicles.
A disadvantage compared to spring-loaded drives such as hollow shafts , cardan discs or spring cup drives is the high mass that lies unsprung on the axle of the tatzlager drive - typically about half the mass of the traction motor, which leads to increased wear on the tracks and gear wheels . According to an LCC study carried out by DB in 2005, the pawl bearing drive is more economical than the hollow shaft drive at speeds of up to 160 km / h.
With DC and single-phase series traction motors , only power outputs of up to 550 kW per axle and speeds of up to 120 km / h were possible with pawl bearing drives. By using asynchronous motors, which have a lower power-to-weight ratio , the power could be increased up to 1400 kW per axis and the speed up to 160 km / h.
Vehicles with a pawl bearing drive (selection)
- heavy freight locomotive of the DR class E 95 , built in 1927
- S-Bahn railcars of the DR class ET 165 , years of construction 1928–1931
- Express locomotive of the DR class E 11 , years of construction 1961–1976
- S-Bahn railcar of the DB class 420 , years of construction 1969–1997
- Diesel locomotive of the DR class 132 / DB class 232 , years of construction 1970–1982
- Express rail car ÖBB B4hET 4020 , years of construction 1978–1987
- Bombardier Traxx locomotives with the usage designation F , years of construction 1997–2002
- Jury Leonid Koffman: The Tatzlager-Motor . In: Wolfgang Messerschmidt (Ed.): Locomotive magazine . No. 88 . Franckh'sche Verlagshandlung, W. Keller & Co. , 1978, ISSN 0458-1822 , p. 15-22 .
- Siegfried Müller: Electric and diesel-electric traction vehicles. Efficiency economy working method . Birkhäuser, Basel 1979, ISBN 3-0348-6551-1 , p. 48 , urn : nbn: de: 1111-20131122384 (Reprint: Springer, Basel 2014.).
- Martin B. Sebald: Comparison of pawl bearing drive and cardan drive with hollow shaft (= ETR - Eisenbahntechnische Rundschau . No. 54 ). Eurailpress - Deutscher Verkehrs-Verlag, Hamburg 2005, p. 455-460 .