Patent GB-1283465-A (GB)
Title: An installation for controlling the extension and retraction of a mast
Inventor: BERTORA MARC
IPC: E04H12/18
Filed: 1970-05-06
Abstract: 1283465 Erecting masts COMMISSARIAT A L'ENERGIE ATOMIQUE 6 May 1970 [7 May 1969] 21828/70 Heading B8B [Also in Division H4] In an installation for controlling the extension and retraction of a mast 5, Fig. 1, made up of sliding elements, a tank 1, which is adapted to be buried and to be enclosed in concrete, is provided at ground level with a manhole 3 having a detachable cover 4 and with an aperture in which is disposed a door comprising two selflocking jaws 31, 32, whose opening is effected by the mast 5 when it rises to extend through them. The installation further includes a double acting self-supporting hydraulic jack comprising a number of telescopic elements, oleopneumatic accumulators and associated compressed air reservoirs for operating said jack, and a control panel comprising a device which is adapted to be remotely controlled via the agency of a delaying relay. As described, the mast 5 provides an aerial for use, for example after a nuclear explosion. An insulated energizing wire 2 is attached to a tensioning spring 7 carried by the aerial head 6 and can slide freely in spacing members 8 attached to the sliding elements of the mast 5, said elements being provided with guiding members to prevent relative rotation. A sheath 9 contains electric cables 10 leading to a remote control centre. Eight accumulators formed by steel reservoirs contain oil in their lower portions and compressed air in their upper portions. Seven accumulators 13, Fig. 4, are for extension of the aerial and one accumulator 14 is for retraction of the aerial. An air compressor and compressed air cylinders are also provided. Hydraulic controls are grouped on a panel 15, and electrical controls on a panel 16. With the aerial fully retracted, receipt of a command signal by landline or radio acts on a delaying system which, after a predetermined time, energizes an explosive link (18), Fig. 5 (not shown), which fractures and allows a plug valve (17) with a calibrated spring to open, and admit pressurized oil from the cylinders 13 to the mast 5, which starts to extend. As the head 6 rises, rollers which it carries engage with extensions of locking levers associated with the jaws 31, 32, which are thereby released (Fig. 2, not shown). Further movement of the head 6, which is of inverted-Vee cross-section, brings it into contact with rollers carried by the said jaws, which are thereby opened, so that the mast can emerge and extend fully. The energizing wire 2 is wound from a drum 34. A counter-wound cable 37 provides means for winding back the wire 2 when the aerial 5 is retracted. The wire 2 is connected to a conductive element of the drum 34 and a contact 46 connects this to an impedance adaptor 45, which allows operations to be performed on two different frequencies, and which is connected to the transmitters or receivers. When the mast is to be retracted, the accumulators 13 are opened to atmosphere, and the accumulator 14 is pressurized. Admission of oil to the upper portion of the lower fixed elements of the mast 5 then effects positive retraction thereof.