TM10-3930-660-34 CHAPTER 10 BRAKE SYSTEM MAINTENANCE Section I DESCRIPTION AND DATA 10-1 GENERAL This chapter covers maintenance procedures for the service brake system components, as well as principles of operation. 10-2 PRINCIPLES OF OPERATION a.    General Hydraulic fluid to operate the service brakes is drawn from the main hydraulic reservoir by the small (1 48 cu in ) section (1) of the dual gear pump. The frame tilt circuit is supplied by the same pump section. Protection for the circuit is provided by relief valve (2), which is designed to bypass when circuit pressure reaches 1750 psi. 10-1