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 PM# July 2006

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 2 AZIMUTH BRAKES CALCULATION Hereunder are reported the azimuth Brakes Calculations

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 3 RESULTS: - Effective brake space = deg; - Effective brake time = sec; - Max deceleration = deg/sec 2 NEW VERIFICATION OF THE ANTENNA STOPPING TIME: - The 300ms was evaluated on the prototype; the tests of maximum time were POSITIVE. - No important improvement increasing the braking force (but increase the deceleration), so the braking force has been maintained. - According to baseline supplier data-sheet the reaction time of brakes plus hydraulic aggregate is 0.1 sec at +20°C; This means a design maximum time = 0.386sec. - Waiting calculation from the brake supplier at –20°C; not expected significant increasing due to the very low viscosity of the chosen oil. - Braking maximum time respected.

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

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 5 Update of POWER HYDRAULIC SYSTEM Main description The system is equipped with 3 delivery oil circuits to the brakes (azimuth brakes, elevation brake and emergency elevation brake), each one controlled by two NC solenoid valve. The pipes are all equipped with an automatic(TBC) discharge system (item E) of possible air accumulated inside the circuit and a pressure transducer for the control of the oil pressure. The actual solution offers the following advantages: Without pump start, the accumulator is able to open the brakes, allowing a power consumption reduction and increase of pump lifetime (the accumulator, with 3,5 litres capacity, is able o fperfoming up to 6 calipers openings, before the pump restart); The accumulator make easier the operations in case of use of the manual pump (in this case, the ball valve (item D) shall be open and the solenoid valve N.O. (item B) shall be operated by means of the provided button);

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 6 The oil is maintained at the working temperature by means of resistors commanded by the thermostat ETS (that commands also the start of the pump); in this way it is also maintained cleaner by filtering; - This heating is still under evaluation. W.r.t. the Prototype, the oil doesn’t stay for long period inside the pipes between the solenoid valve and the caliper, but is quite often flushed; The non-return valve (item C) maintains the pipes always filled by oil; so, in case of manual pump operations, very few manouvres are needed.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 7 Hydraulic power unit – proposal