Travel Speed
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| Illustration 1 | g01166544 |
Cross Section
Each propel motor drives a track through a two-speed planetary final drive. The right and left final drive assemblies are identical. The final drive assembly contains three planetary gear assemblies and a mechanical shifting mechanism. The mechanical shifting mechanism consists of the following components:
- Gear selector piston
- Coupler
- Two springs
The auxiliary hydraulic system supplies oil in order to move the gear selector piston and the coupler.
Lubrication System
Components that are inside the planetary final drive are lubricated by the hydraulic oil that splashes on the components. The housing serves as the oil reservoir.
Oil Flow
When the machine is in the TRAVEL mode, the shift solenoid directs supply oil into the shift passage. This passage is located inside the final drive. The shift passage delivers oil to the chamber at the right of the gear selector piston. See Illustration 1. Oil pressure in this chamber acts against one side of the gear selector piston. Springs act against the other side of the piston.
Gear Selector Piston and Coupler
When the machine is in the TRAVEL mode, the force from the oil pressure which is in the piston chamber causes the gear selector piston and the coupler to move against the force of the springs. Eventually, the coupler engages the first stage sun gear. The coupler connects the first stage sun gear with the drive shaft. The drive shaft is splined to the brake coupling. The second stage sun gear is also splined to the brake coupling.
First Stage Planetary
When the machine is moving, the output shaft of the propel motor turns the first stage sun gear. The coupler is engaged with the first stage sun gear when the machine is in the TRAVEL mode. As a result, rotation of the first stage sun gear causes the second stage sun gear to rotate.
Second Stage Planetary
In the second stage planetary, the sun gear is driven and the ring gear is held. Therefore, the interaction between the second stage sun gear and the second stage planetary gears causes the second stage planetary carrier to rotate. The second stage planetary carrier is connected to the third stage sun gear.
Third Stage Planetary
In the third stage planetary, the sun gear is driven and the planetary carrier is held. Under these conditions, the planetary gears cause the third stage ring gear to rotate. The third stage ring gear is connected to the hub. The hub transfers power to the drive wheel.
Pave Speed
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| Illustration 2 | g01166241 |
In the second stage planetary, the sun gear is driven, and the ring gear is held. Therefore, the interaction between the second stage sun gear and the second stage planetary gears causes the second stage planetary carrier to rotate. The second stage planetary carrier is connected to the third stage sun gear.
In the third stage planetary, the sun gear is driven, and the planetary carrier is held. Under these conditions, the planetary gears cause the third stage ring gear to rotate. The third stage ring gear is connected to the hub. The hub transfers power to the drive wheel.
Oil Flow
When the machine is in the PAVE mode, the shift solenoid delivers oil to the hydraulic tank from the shift passage. In the PAVE mode, the springs that act against the gear selector piston and the springs that act against the coupler cause these components to move to the right. See Illustration 2. The coupler engages the first stage planetary carrier. Engagement of the first stage planetary results in a gear reduction when the machine is moving.
First Stage Planetary
In the first stage planetary, the first stage sun gear is driven by the motor output shaft, and the first stage ring gear is held. As a result, the interaction between the first stage sun gear and the first stage planetary gears causes the first stage planetary carrier to rotate. This rotation causes the drive shaft to rotate. Rotation of the drive shaft causes the second stage sun gear to rotate.
Second Stage Planetary
In the second stage planetary, the sun gear is driven, and the ring gear is held. Therefore, the interaction between the second stage sun gear and the second stage planetary gears causes the second stage planetary carrier to rotate. The second stage planetary carrier is connected to the third stage sun gear.
Third Stage Planetary
In the third stage planetary, the sun gear is driven, and the planetary carrier is held. Under these conditions, the planetary gears cause the third stage ring gear to rotate. The third stage ring gear is connected to the hub. The hub transfers power to the drive wheel.