349F and 352F Excavators Hydraulic System Final Drive Caterpillar


Final Drive
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349F and 352F Excavators Hydraulic System [UENR2954]
POWER TRAIN
DRIVE GP-FINAL
349F and 352F Excavators Hydraulic System Final Drive
1.1. Operation


Illustration 1g02175550
Final drive
(1) Roller bearing
(2) Planetary shaft (second stage)
(3) Bolt
(4) Planetary gear (second stage)
(5) Roller bearing
(6) Planetary gear (third stage)
(7) Roller bearing
(8) Planetary shaft (third stage)
(9) Drive sprocket housing
(10) Motor housing
(11) Travel motor
(12) Planetary gear (first stage)
(13) Planetary shaft (first stage)
(14) Cover
(15) Sun gear (first stage)
(16) Planetary carrier (first stage)
(17) Ring gear (first stage)
(18) Planetary carrier (second stage)
(19) Sun gear (second stage)
(20) Ring gear (second stage and third stage)
(21) Planetary carrier (third stage)
(22) Sun gear (third stage)
(23) Output shaft (travel motor)
(24) Coupling
(25) Gear coupling
(26) Roller bearing

The final drive reduces the rotational speed of travel motor (11). Output shaft (23) of travel motor (11) is splined to sun gear (first stage) (15) by coupling (24).

The final drive consists of two groups. The first group consists of the three stages of the planetary gear reduction. The second group is the output group.

  • The first stage reduction group consists of the following components: sun gear (15), planetary gear (12), planetary carrier (16) and ring gear (17). The group for second stage reduction consists of the following components: sun gear (19), planetary gear (4), planetary carrier (18) and ring gear (20). The third stage reduction group consists of the following components: sun gear (22), planetary gear (6), planetary carrier (21) and ring gear (20).

  • The output group operates in the following manner. The rotation of drive sprocket housing (9) drives the track. Drive sprocket housing (9), ring gear (20), and cover (14) are connected by bolts (3). The drive sprocket housing, the ring gear, and the cover are supported by roller bearing (26). This planetary assembly rotates with ring gear (20).

The planetary gears reduce the travel speed by the ratio of the teeth of the sun gear to the teeth of the ring gear.

Operation

Sun gear (15) is splined to the output shaft (travel motor) (23). The rotation of the output shaft is transmitted to the sun gear. When the sun gear rotates clockwise, the final drive operates in the following manner:



Illustration 2g02161978
First stage reduction group
(1) Roller bearing (first stage)
(12) Planetary gear (first stage)
(13) Planetary shaft (first stage)
(15) Sun gear (first stage)
(16) Planetary carrier (first stage)
(17) Ring gear (first stage)
(27) Rotational direction (first stage reduction group)

In the first stage reduction group, sun gear (15) causes planetary gears (12) to rotate counterclockwise. Planetary gears (12) mesh with sun gear (15) and ring gear (17). Planetary gears (12) rotate around sun gear (15) and the internal teeth of ring gear (17). Each planetary gear (12) is mounted to planetary carrier (16) by shaft (13) and by roller bearing (1) in order to form a planetary assembly. Planetary carrier (16) rotates in a clockwise direction (27).



Illustration 3g00581164
Engagement of splines
(12) Planetary gear (first stage)
(13) Planetary shaft (first stage)
(16) Planetary carrier (first stage)
(19) Sun gear (second stage)
(28) Engagement of splines

The spline of the planetary carrier (first stage) (16) meshes with the sun gear (second stage) (19). The rotation of planetary carrier (16) is therefore transmitted to sun gear (19). Sun gear (19) rotates clockwise.

In the group for second stage reduction, sun gear (19) causes planetary gears (4) to rotate counterclockwise. Planetary gears (4) mesh with sun gear (19) and ring gear (20). Planetary gears (4) rotate around sun gear (9) and the internal teeth of ring gear (20). Each planetary gear (4) is mounted to planetary carrier (18) by shaft (2) and by roller bearing (5) in order to form a planetary assembly. Planetary carrier (18) rotates clockwise.



Illustration 4g00581172
Engagement of splines
(18) Planetary carrier (second stage)
(22) Sun gear (third stage)
(27) Engagement of splines

The spline of the planetary carrier (second stage) (18) meshes with sun gear (third stage) (22). The rotation of planetary carrier (18) is transmitted to sun gear (22). Sun gear (22) rotates clockwise.

In the third stage reduction group, the spline teeth of planetary carrier (21) mesh with teeth on the outer circumference of motor housing (10) via gear coupling (25). Since motor housing (10) is fixed to the track frame, planetary carrier (21) does not rotate.

Planetary shaft (8) is stationary. The planetary gear (third stage) (6) rotates around planetary shaft (8). Since planetary carrier (21 ) is attached to the track frame and the planetary carrier does not move, ring gear (20) rotates counterclockwise. Since ring gear (20) and drive sprocket housing (9) are held together with bolts (3), drive sprocket housing (9) rotates counterclockwise. This causes the right track to move in a forward direction.

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