Abstract: A photoelectric control unit for street lighting comprises control means including a photoelectric sensor mounted on a printed circuit board for switching on a street lamp when the intensity of light falling on the sensor falls below a preset value. Electrical connection means between the P.C.B. and the lamp is provided by three connector pins which are led through a cooling chamber or stem. The pins are cranked to closely follow the contour of the chamber to dissipate heat through the chamber walls. The chamber is also filled with a high thermal conductivity potting compound for heat transfer to the walls of the chamber.One controller for such a photoelectric control unit includes a switching means provided by a relay and a triac connected in parallel. The triac operates to prevent the relay being subjected to high voltages during switching and hence prevents pitting of the relay contacts.

Abstract: A trailer comprises a container supported between a pair of scissors lifts having first and second arms movable about a pivot by a ram. The arms support the container by a pair of rollers and a mounting lug. The mounting lug comprises a lug on the container for engagement with a pair of U-shaped slots, a tilt slot and a lift slot. The lug engages the lift slot when the trailer is to be lifted. For tilting the lug engages the tilt slot thereby causing the rollers to disengage the container to permit tilting.