21:10. Repair of a forward support of FN-3

Fig. 15-19. Forward support of FN-3: 1 – protective cap; 2 – the directing finger, 25 N · m; 3 – pumping union; 4 – protective cover; 5 – support; 6 – spring; 7 – plug; 8 – holder of a support; 9 – sealing ring; 10 – piston; 11 – protective cover

Details of a forward support of FN-3 are shown in fig. 15-19.
Clear a support of dust and dirt, without inhaling the kicked-up dust.
Fix a support in a vice. Take the piston from a support for what give air under low pressure to the brake cylinder through an opening for connection of a brake hose, having established wooden whetstone instead of brake shoes.

Fig. 15-20. Use of an assembly wedge for extraction of consolidation from a support cylinder flute

Remove wooden whetstone and carefully take the piston. Accurately, not to damage a cylinder wall, take out consolidation from a support cylinder flute an assembly wedge or an edge of the flat screw-driver as the lever (fig. 15-20).
Check a condition of all details of a support and replace the worn-out or damaged details. Pay special attention to the cylinder and the piston. In the presence of scratches, рисок, wear or pointed corrosion it is necessary to replace the piston and the cylinder. Irrespective of a state replace all rubber consolidations.
Wash out all details in methyl alcohol or pure brake fluid and wipe them. Blow tubes and openings compressed air.

Fig. 15-21. An installation site of a protective cover on the support piston

Apply a thin film of A2 G 052 150 lubricant on a sealing ring and the piston (fig. 15-21).
Install a dustproof cover on the piston so that the internal diameter of a cover was included into a piston flute.

Fig. 15-22. Use of special device for installation of a working edge of a dustproof cover in a support

Install the piston opposite to the cylinder of a support and special adaptation insert a working edge of a dustproof cover into a support before its fixing (fig. 15-22).
By means of special adaptation or the handle of the hammer press the piston into the support cylinder.
After installation of the piston blow air the cylinder and fill it with fresh brake fluid.