TM 9-2320-361-10 2-27. OPERATION OF WATER TANK TRUCKS (Contd) NOTE M50A2 has separate water level gages for front and rear tanks. M50A3 has one gage for both tanks. (2) Remove water level gage (12), and measure water level. (3) If less than 10 inches of water in tank, add water (refer to b, c, or d of this para.), or move water from one tank to another. (4) To move water from one tank to another: (a) Turn pump delivery line discharge valve knob (13) and gravity delivery line suction valve knob (3) right, to closed position. (b) Pull compartment valve levers (1) and (2) back, to open position. (c) When low tank reaches 10 inches, push compartment valve levers (1) and (2) forward, to closed position. (5) Remove pump delivery line discharge valve dust cover (14) and gravity delivery line suction pump dust cover (6), and turn knobs (13) and (3) left, to open position. During freezing temperaturest always keep delivery lines, compartment drain pipes, manifold pipes and delivery pump free of water, except during water discharging operations. Water in system may freeze and damage compartments. 2-129