Abstract: The invention is with respect to a fail-safe system for stopping damage to water boilers, whose thermostats are not in working order.In an automatic combustion control system of the sort having an elastic thermostat bellows element placed within an outer shell within the water space of a boiler and joined by a chain or the like with the air door for controlling the air inlet rate at some point in the connection between the thermostat element and the door, there is a temperature-sensitive part, for example in the form of a plug of fusible metal or collapsing material, or in the form of a soldered join using a special fusible solder.In one form of the invention, this temperature-sensitive part may take the form of a ring of temperature-sensitive material placed at one end of a spring which is forced together on the temperature increasing.

Abstract: In the case of a pressure-worked automatic control system with a closed loop, and, more specially, a position automatic control system, the position of a servo-element is dependent on a spring placed between the servo-element or servo-motor and the sensing unit of the position automatic control system. The spring, placed between the servo-element or servo-motor and the sensing unit of the position automatic control system, is made up of at least one spiral spring, whose one end is able to be turned by a moving servo-part of the servo-element or servo-motor, while its other end is designed for acting on the sensing unit of the position automatic control system.

Abstract: A turning boring head or the like has a tool, designed for radial adjustment, and whose tool support is able to undergo feed motion, using liquid power into a position dependent on the desired size of the bore being machined. The bore rod body has not only a pressure medium powered tool support designed for fine positioning of the fine-adjustment cutting tool, but furthermore at least one further tool support for a further cutting tool.