Bottom Track and Bottom Retrofit Bracket

Using a 1/8 in. (3 mm) drill bit, drill out both of the rivets on the horizontal bus barrier bracket (the L-shaped bracket located on the topshelf—see Horizontal Bus Barrier (L-shaped) Bracket). Remove the bracket and discard it.

To install the bottom retrofit track, follow step a if you have a welded topshelf, or step b if you have a relay topshelf (see Welded and Relay Topshelf Assemblies):

1. Welded topshelf: Align the holes of the shelf with those on the bottom track (see Welded and Relay Topshelf Assemblies). Rivet the track and the retrofit bracket to the topshelf.

   NOTE: If the bus contains four laminations, access the rivet holes from underneath the topshelf.

2. Relay topshelf: Align the two holes on the relay shelf with the bottom retrofit bracket holes (see Welded and Relay Topshelf Assemblies). Mark the places where you will drill other holes to secure the bottom track to the shelf. Drill the holes using a drill bit ranging from 0.136 in.–0.147 in. (3 mm–4 mm) in diameter. Rivet the track and retrofit bracket to the topshelf.

   NOTE: The bottom retrofit track can be riveted directly onto the relay topshelf only if the relay assembly topshelf has two holes instead of four.