Usage:
789B (7EK),
793B (1HL) Trucks
- SUPPLEMENT: 12/23/96
Service Magazine; August 19, 1996; Page 9; "New Orifice Plate To The Rear Brake Cooling Return Oil Line Significantly Reduces Hub Wear" for 789B (7EK) and 793B (1HL) Trucks.
Insert the following reference above the "Description Of Change:"section.
Reference: Service Magazine; August 19, 1996; Pages 7 and 8; "New Seal Retainers And Backing Plate Used To Reduce Oil Leaks And Provide An Increased Face Load On Duo-Con Seals."
The last sentence of the "Adaptable To:" section is incorrect and should be replaced with:
This change affects the 789B (7EK283-457) and 793B (1HL205-499) Trucks and any trucks with increased face load seal retainers.
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Description of Change: A new orifice plate has been added to the rear brake cooling return oil lines for the 789B and 793B Trucks. On certain 789B and 793B Trucks, the brake hub may rub against the brake housing due to the increased face load on the duo-cone seals. This modification will significantly reduce hub wear on the housing.
Adaptable To: The 789B Truck uses two 137-4276 Orifice Plates with eight longer 8T-4835 Bolts and two 6J-2680 Seals. The 793B Truck uses two 137-4275 Orifice Plates with eight longer 8T-4140 Bolts and two 2H-6338 Seals. The quantities listed will modify both the left and right rear brake lines. Insert the orifice plates, seals and longer bolts at the hydraulic tank connections for the return oil lines from the rear brakes. The change is effective with 789B (7EK283-457) and 793B (1HL205-499) Trucks.
NOTE: The change is adaptable to all earlier machines ONLY IF new seal retainers are added.
Illustration 1. Typical view of location of 137-4275 Orifice Plate (1) for 789B Trucks.
Illustration 2. Typical view of location of 137-4275 Orifice Plate (1) for 793B Trucks.