Patent GB-997860-A (GB)
Title: Improvements in switch cabinets
IPC: H01H9/22
Filed: 1961-05-10
Abstract: 997,860. Releasable fastenings. SQUARE D CO. May 10, 1961 [Aug. 17, 1960], No. 16936/61. Headings E2A and E2B. [Also in Division H2] A switch cabinet has an opening 8, at one side, a door 9 hingedly mounted for movement to open and closed positions relative to the opening and fastening means comprising a rock lever 20 mounted on the door at the inner face thereof for rocking about an axis extending in a direction forwardly and rearwardly of the door, an exterior handle 22 mounted on the door and operable to rock the lever 20, the lever having a roller 23 thereon rotatable about an axis extending radially from the axis of the lever and adapted to engage and roll along an inner face portion of the cabinet as the lever is rocked about its rocking axis from its releasing to its fastening position, said roller being tapered axially in a direction outwardly from said rocking axis so that as it rolls towards the fastening position along the inner face portion it progressively presses the door more firmly into closed position. In the construction shown a second rock lever 24 having a tapered roller 25 is also pivotally mounted on the door and is connected to the rock lever 20 by a link 26 so that both rock levers are operated by the handle 22. A spring 28 biases the rock levers to the releasing position. Mechanism 30 is provided to prevent the door being unfastened without the use of a tool and comprises a latching lever 31 mounted on the door by means of a pivot 32 so that it pivots about an axis parallel to the axes of the rock levers 20, 24. The lever 31 is biased by a spring 33 towards a latching position in which it prevents the rock levers being unfastened; to achieve this the lever 31 has a shoulder 34 which in the latching position engages a shoulder 35 of the rock lever 20. The pivot 32 of the lever 31 rotates with the lever and its outer end has a screw driver slot 36 which enables the lever to be rotated in an anti-clockwise direction against the bias of the spring 33. This anti-clockwise rotation of the lever 33 by the use of a screw driver separates the shoulders 34 and 35 and enables the rock levers to be moved by the handle 22 to the releasing position. Since the lever 31 is biased by its spring 33 to the latching position, it occupies its latching position while the door is unfastened. To move it out of the way therefore when the door is moved to closed position it is provided with a cam surface 37 which during closing movement of the door is engaged by a flange 11 around the opening 8 to cam the lever away from its fastening position. Should the levers be in the fastening position while the door is open this movement of the lever 31 will move the shoulder 34 out of engagement with the shoulder 35 and allow the levers to move to the releasing position under the bias of their spring 28. When the lever 31 has passed the edge of the door it returns to its fastening position and prevents the door being opened without the use of the screw driver in the slot 36. The switch in the cabinet includes a contact carrier 40 which carries contacts 41 movable to opened and closed positions with respect to stationary contacts 42; the carrier 40 is connected to a bail 43 having radially extending arms 44 which are pivotally connected to supports by pivots 45 so that the bail can be swung about an axis extending horizontally transversely of the cabinet. The bail is moved to positions which open and close the contacts by means of a handle 51 pivotally mounted on a housing 50 on the outside of the cabinet. The housing and handle are both provided with holes 54, 54a through which a padlock can be passed to lock the handle in the on position of the switch. They are also provided with slots 53, 57 through which up to three padlocks can be passed to lock the handle in the off position of the switch. The handle is rigidly connected to a disc 58 in the housing so that the disc rotates with the handle and this disc is connected to a disc 46, which operates the bail to its on and off positions, by means of a rod 59, the rod being pivoted to the disc 58 and having a pin and slot connection with the disc 46. The pin on the rod is urged to the right-hand end of the slot 60 of the disc by a spring 61. The disc 46 is biased to two alternative positions corresponding to the open and closed positions of the switch contacts by an over-centre mechanism comprising a rod 62 and a spring 66 which engage a slot 63 in the disc 46. Movement of the disc is limited by engagement of abutments 75, 78 on the disc with stops carried by the cabinet. The disc moves the bail by means of lugs 48, 49. A latching mechanism 79 is provided to prevent the switch contacts being in the closed position while the door is open and to prevent the door being opened when the switch is in the closed position. The mechanism 79 comprises a latch lever 80 which is pivotally mounted in the housing 50 by means of a pivot 81 rigidly connected to the lever; the lever 80 is biased by means of a spring 82 in a direction towards the disc 58 and has a detent 84 which can engage a shoulder 83 on the disc 58 to prevent the handle 51 being moved more than a short way from the off position towards the on position. A hook 91 on the door engages with a finger 90 on the lever 80 when the door is in closed position and the switch handle 51 is in other than the off position to prevent opening of the door. In the off position of the handle 51 a cam surface 92 holds the lever 80 in a position such that the finger is disengaged from the hook 91. In any other position of the handle 51 the finger can only be disengaged from the hook by using a screw driver in a slot 87 of the pivot 81 of the lever. To enable the switch handle 51 to be moved to the on position when the door is closed and fastened a lug 96 is provided on the link 26 which joins the two rock arms of the door fastening mechanism. When the door is fastened by the arms the lug engages the finger 90 and swings the lever 50 to a position in which it does not interlock with the shoulder 83 of the handle 51. In a modification the lug 96 is omitted; in this construction the hook 91 has a cam surface arranged so that as the door is moved to closed position its depresses the lever 80 until it engages behind a shoulder on the hook; the lever 80 is then in such position that it cannot prevent movement of the handle 51 to its "on" position.