35. The elevators shall be controlled by three-way valves, arranged to admit water from the pressure tank to the cylinders, and to discharge from the cylinders into the suction tank in the pump-room. The valves shall be designed in accordance with the standard practice for hydraulic elevators, with cup leather packings and graduated port openings.
Packings shall be readily accessible for replacement. The valves shall be absolutely tight when in the closed position to prevent "creeping" of the elevators.
36. Each valve assembly shall consist of six (6) valve units, three for admission and three for discharge. Each unit shall be operated by water pressure admitted to its operating cylinder by a solenoid pilot valve. Speed control of the elevators shall be affected by means of a master switch located at the control station, which shall govern the opening of the individual valve units.
37. Directional control shall be effected by means of push-button operating stations, located on the stage as directed, and shall govern the opening of the admission or discharge group of valves as required. Buttons shall be provided for the High, Stage and Basement and Sub-basement levels, with additional buttons for stopping the elevators at any other level desired. Automatic stops for each elevator corresponding to the levels indicated by the push buttons shall be effected by means
of a geared selector switch driven from the equalizing shaft. The opening of the contacts of the selector switch shall close the elevator operating valves corresponding to the direction of travel of the elevator. The selector shall be provided with auxiliary contacts, arranged to operate by-pass valve to automatically correct "creeping" of the elevator due to any small leakage which may occur when the elevator is at stage level, by either admitting or discharging water as required. The leveling device shall be designed to maintain the correct position within one-eighth (1/8") inch.
38. The entire selector device shell be enclosed in a water-tight casing, which shall be readily accessible for inspection and adjustment.
39. The necessary relays and switches for the control of each elevator shall be mounted on slate panels and installed in the pump-room. Wherever necessary, all wiring shall be in water-proof conduit.
40. A system of indicators shall be provided which shall indicate to the elevator operator at all times the relative positions of the elevators, as well as the relative speeds of each elevator.
41. Wiring:
All wiring between push buttons, relays, selectors and pilot valves shall be installed by the elevator contractor, and also wiring from pump motors to starters and automatic pressure switches. Wiring shall conform to the requirements of the National Board of Fire Underwriters, and also the Electrical Code of the City of New York.