Abstract: A road brake automatic slack adjuster mechanism having input and output members each pivotable about a common axis to apply and release a brake-applying force. These two members are interconnected by a force-transmitting member which, on the one hand, is threadedly engaged with the output member and, on the other hand, is releasably clutched to the input member. To effect slack adjustment, the mechanism includes brake-clearance determining device settable to predetermine the required brake clearance. This brake-clearance determining device includes a stepless clutch which interconnects the brake-clearance determining device and the output member. The clutch is released upon pivotal movement of the output member in a brake-force applying direction, equating with the required brake-clearance to allow the clutch to slip during movement of the output member corresponding to excessive clearance.

Abstract: A slack adjuster for railway brakes has an input member to which a brake force is applied and an output member movable coaxially therewith, a coupling element via which a brake force is transmissible between the two members and which is positively engaged with one of the members via a cooperating helical engagement means and is engageable with the other member via clutching faces which are retained in force transmitting engagement by the reaction forces produced by the helical engagement means when a force is transmitted between the members for a brake application, the clutching faces being disengageable when such reaction forces are removed to permit relative rotation of the members and enable wear or slack in the brake rigging to be taken up.

Abstract: Slack adjusting means comprises a linearly movable input member, a linearly movable output member, and an element for transmitting a brake force from the input member to the output member, characterized in that the input and output members are constrained against relative angular movement, and in that the element is engaged with one of said members via co-operating helical thread means provided therebetween and is engageable with the other of said members via co-operable clutch faces provided therebetween and arranged such that in use the clutch faces are retained in force-transmitting engagement by the reaction forces in the co-operating helical thread means and are disengageable when said reaction forces are removed or relieved thereby to permit relative rotation, and hence relative linear displacement corresponding to the slack to be taken up, between the element and said one member in engagement therewith via the co-operating helical thread means.

Abstract: A vehicle door arrangement in which a lower edge part of the door is retractable upwards into the main part of the door prior to opening. This ensures that when the vehicle is standing alongside a platform, there is no risk of the bottom of the door fouling the platform. The arrangement is particularly suitable for slide and plug doors which move outwards and then alongside the vehicle when opening. Even if the bottom of the door is normally above the platform, the invention provides an essential safety feature to cope with situations where the vehicle is abnormally depressed, e.g. by excessive loading or suspension failure. Moreover, the invention enables the height of the interior floor of vehicle to be optimized with respect to platform level so as to enhance passenger safety and convenience, whereas with prior art rigid one-piece doors, clearance requirements dictated non-optimum floor heights.