308C CR Excavator Hydraulic System – Swing Drive

The swing drive consists of a series of planetary gears. The planetary gears reduce speed of rotation of the swing motor. The swing motor is bolted to the swing drive. The swing drive is bolted to the upper structure. The teeth of the swing drive output pinion shaft (11) engage with bearing gear (10) of the swing bearing. As pinion shaft (11) rotates counterclockwise, pinion shaft (11) moves in a clockwise direction around bearing gear (10). This causes the machine to swing. Bearing gear (10) is attached to the lower structure.

Swing motor output shaft (3) is splined to first stage sun gear (4). First stage planetary gears (1) of first stage carrier (2) mesh with first stage sun gear (4). When first stage sun gear (4) rotates counterclockwise, first stage planetary gears (1) rotate in a clockwise direction on the shafts of the first stage planetary carrier. First stage planetary gears (1) move counterclockwise around the ring gear. First stage carrier (2) rotates counterclockwise.

The inner circumference of the first stage carrier (2) engage with the splines on the second stage sun gear (5). This causes second stage sun gear (5) to rotate counterclockwise when the first stage carrier rotates. Splines on second stage carrier (7) engage with the splines on second stage sun gear (5). Second stage planetary gears (6) turn clockwise on the shafts and second stage planetary gears (6) move in a counterclockwise direction around the ring gear. While second stage carrier (7) is supported by bearing (9), the carrier turns counterclockwise. The splines on the inner circumference of second stage carrier (7) engage with the splines of pinion shaft (11). When the second stage carrier turns clockwise, pinion shaft (11) rotates counterclockwise.