Large wheel

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Large wheel in the construction of the Buchli drive

Large wheel with attachment on the drive axle for the SLM universal drive

The large gear is colloquially referred to as the gear part of the spur gear of the single axle drive , which is connected directly or indirectly to the gear set . Since the transmission ratio is naturally less than 1, this designation has become common.

history

Originally , the large wheel was shrunk onto the drive axle of the first electric locomotives , which already had the pawl bearing drive as a single axle drive. The power transmission took place unsprung to the drive wheels. This was unfavorable for the start of the locomotive, and the shocks from the superstructure were transmitted unsprung to the traction motors. Therefore, there were various developments of the single axle drive with different bearings and transmission types of the large wheel.

In later developments, the torque arm was improved in pawl bearing drives and the transmission from the large wheel to the drive wheel took place via spring-loaded elements. With the Buchli drive , the large wheel is stored in the locomotive frame. The transfer to the wheelset was done via coupling rods and toothed rockers, which enabled the height compensation. In the case of the SLM universal drive, the transmission from the large wheel mounted in the locomotive frame was carried out via a connecting coupling. With all other types of drive, the large gear is mounted on a hollow shaft, which enables height compensation. The torque is transmitted to the wheels via spring-loaded elements. More recently, rubber elements have been used.

The gearing is mostly straight, but there were single-axis drives with helical or herringbone spur gears. During operation, the large gear is enclosed in a protective box together with the drive gear of the traction motor, where the spur gear is also lubricated. Superheated steam oil is used for this. The large wheel and the drive wheel of the locomotive form an assembly unit. When changing the drive axle, e.g. B. in flat spots , the large wheel is therefore changed with. The large wheel is only separated from the drive axle in a repair shop with special manufacturing facilities for thermal expansion .