Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 1 Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas Brakes System Design PM# June 2006

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 2 ACTIVITIES DEVELOPED - Calculation activities; - Activities of analysis of possible suppliers; - Design Activities. AZIMUTH BRAKES CALCULATIONS RESULTS - N°3 equal calipers; Specification Requirements: a)Able to stop the antenna at the maximum speed within 0.5 sec: Verified = sec braking time, calculated from the point on which the pads touch the race) b)Able to prevent motion with the maximum torque applied to the motors: Verified; c)Able to keep the antenna in any parked position and with wind up to 30 m/sec: Verified

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 3 ELEVATION BRAKES CALCULATIONS RESULTS - N°2 calipers: N°1 Operational + N°1 Survival; Specification Requirements: a)Able to stop the antenna at the maximum speed within 0.5 sec: Verified; b)Able to prevent motion with the maximun torque applied to the motors: Verified; c)Able to keep the antenna in any parked position and with wind up to 30 m/sec: Verified; Added request: Able to prevent motion with snow accumulation of 50kg/m^2 in the reflector: Verified.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 4

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 5 POWER HYDRAULIC SYSTEM Main description The system is equipped with 3 oil delivery circuits to the brakes (azimuth brakes, elevation brake and emergency elevation brake), each one controlled by a NO solenoid valve and a NC solenoid valve. The pipes are all equipped with an automatic discharge system of possible air accumulated inside the circuit and a pressure switch for the control of the oil pressure. As regards to the hydraulic circuit of the prototype, the antenna is equipped with: an accumulator that, besides to keep constant the pressure in the pipes, allows to speed up the opening phase of the brake ; a thermostat ETS that, if the oil reaches a low temperature, commands the start of the pump and allows towards a fluxing inside the 3 circuits to keep the characteristics of the oil in the current point of work (TBC). Bleeders, for the installation and commissioning of the system, will be added on the circuit points tbd by the pipes paths.