Usage:
446B (5BL1-UP)
The 446B Backhoe Loaders have used transmission arrangements that are separated into two categories, Two-Wheel-Drive (2WD) and All-Wheel-Drive (AWD). There have been three versions of transmission arrangement in each category. The chart above shows the effectivity for both the transmission arrangements and the machines.
The 7T-8519 and the 7T-8520 Transmission Arrangements were the first units used in production. The 7T-8519 Transmission Arrangement was used on the AWD 446B Backhoe Loaders. The 7T-8520 Transmission Arrangement was used on the 2WD 446B Backhoe Loaders.
Several changes were made to these units. The former transmission control group was replaced with a new and improved transmission control. The new transmission control group provided greater reliability of the shifter control.
Several wiring harness updates, the removal of a pressure switch and its manifold from the transmission hydraulic control valve, and the change to the transmission control group created the next versions of transmissions. These were the 123-1022 and the 123-1024 Transmission Arrangements.
The 123-1022 Transmission Arrangement was used in the 2WD 446B Backhoe Loaders. The 123-1024 Transmission Arrangement was used in the AWD 446B Backhoe Loaders.
Customers with the 7T-8519 and the 7T-8520 Transmission Arrangements with the former transmission control group can upgrade to the new transmission control group. The 125-7130 Transmission Shifter Kit allows the 7T-8519 and the 7T- 8520 Transmission Arrangements to use the new transmission control group.
Changes to the 123-1022 and the 123-1024 Transmission Arrangements created the current production arrangements, the 122-9220 and the 122-9221 Transmission Arrangements. The 122-9220 Transmission Arrangement is used in the 2WD 446B Backhoe Loaders. The 122-9221 Transmission Arrangement is used in the AWD 446B Backhoe Loaders.
The current production transmissions are referred to as "Single Pressure" transmissions because there is no difference in the pressure between the speed clutches and the pressure between the directional clutches.
These units use the new transmission control group used in the previous transmission arrangements. Several changes to the transmission hydraulic control valve and clutch packs provide a smoother shifting, more reliable transmission.
The clutches received several changes. These include: larger, new style pistons; the clutch cylinder snap rings were replaced with new spiral-lock rings for easier servicing; spring washers were removed; extra friction discs were added to some clutches; and conventional friction discs and plates were removed from the second speed clutch and replaced with new style, single piece "Single Face" friction disc/clutch plates to add more surface area.
Due to the type of changes to the clutch groups, only the 122-9226 Transfer Drive Group in the 122-9221 Transmission Arrangement of the All-Wheel-Drive machines can be interchanged with the groups in the previous AWD transmission arrangements.
The chart above shows the changes between the three versions of the Two-Wheel-Drive transmission arrangements.
The chart above shows the changes between the three versions of the All-Wheel-Drive transmission arrangements.