Abstract: A method of controlling total jet pressure from the head of a metallurgical lance for introducing gas into a volume of metal in a vessel. The lance head has at least one ejector, which has a nozzle located in a bore of the lance head and has an annular gas passage between at least one nozzle and the wall of the bore. The method proceeds by adjusting the annular gas velocity from a first Mach number to a second mach number to effect change of the total jet pressure.

Abstract: A metallurgical lance for introducing gas into a volume of molten material in a furnace includes a head having a bore extending therethrough, a mounting assembly at the head in the bore, and a nozzle detachably secured to the mounting assembly by a connection, the nozzle adapted to coact with a tool releasably engagable with the nozzle to insert and withdraw same from the lance head through the bore without dismantling the nozzle.

Abstract: A string trimmer comprising an elongate shaft; a cutting head rotatably mounted on one end of the elongate shaft; at least one cutting member which extends from the cutting head and a barrier which is capable of being used by an operator to move vegetation away from a path swept out by the cutting member when it rotate characterized in that the barrier is pivotally mounted about a single pivot axis on the string trimmer and, when the cutting head is rotating in a flat position is capable of pivoting from a position above the path swept out by the cutting member to a position below the path swept out by the cutting member without passing through the path swept out by the cutting member.

Abstract: A string trimmer comprising an elongate shaft and a cutting head rotatably mounted on one end of the shaft. A cutting member which extends from the cutting head. An attachment is pivotally mounted on the string trimmer by at least one pivot mechanism, wherein the pivot mechanism comprises a latching mechanism about which the attachment is capable of latchably rotating relative to the string trimmer. The attachment is a barrier which is capable of being used by an operator to move vegetation away from a path swept out by the cutting member.

Abstract: A string trimmer having an elongate shaft, a cutting head rotatably mounted on one end of the elongate shaft, at least one cutting member which extends from the cutting head, and a barrier which is capable of being used by an operator to move vegetation away from a path swept out by the cutting member when it rotates. The barrier is in the shape of a truncated sphere, and forms a broad band. There is further provided a guard on the string trimmer mounted on the elongate shaft which surrounds part of the rear of the path swept out by the cutting member as it rotates, wherein the barrier is mounted on the guard.

Abstract: A string trimmer comprising an elongate shaft; a cutting head rotatably mounted on one end of the elongate shaft; at least one cutting member which extends from the cutting head and a barrier which is capable of being used by an operator to move vegetation away from a path swept out by the cutting member when it rotate characterized in that the barrier is pivotally mounted about a single pivot axis on the string trimmer and, when the cutting head is rotating in a flat position is capable of pivoting from a position above the path swept out by the cutting member to a position below the path swept out by the cutting member without passing through the path swept out by the cutting member.

Abstract: A string trimmer comprising; an elongate shaft; and a cutting head rotatably mounted on one end of the shaft; a cutting member which extends from the cutting head; an attachment mounted on the string trimmer; the attachment being pivotally mounted on the string trimmer by at least one pivot mechanism wherein the pivot mechanism comprises a latching mechanism about which the attachment is capable of latchably rotating relative to the string trimmer. The attachment is a barrier which is capable of being used by an operator to move vegetation away from a path swept out by the cutting member.

Abstract: A string trimmer comprising an elongate shaft; a cutting head rotatably mounted on one end of the elongate shaft at least one cutting member which extends from the cutting head and a barrier which is capable of being used by an operator to move vegetation away from a path swept out by the cutting member when it rotates characterized in that the barrier in the shape of a truncated sphere is in the form of a broad band. There is further provided a guard on the string trimmer mounted on the elongate shaft which surrounds part of the rear of the path swept out the cutting member as it rotate wherein the barrier is mounted on the guard.

Abstract: Radio communication apparatus for transmitting control data, comprising output power amplifying means responsive to a control signal from an output power control means for varying a predetermined output power level from the output power amplifying means in accordance with a sequence of power levels indicative of a control message. The predetermined output power level is selectable from a range of predetermined power levels and may be variable between power levels of adjacent predetermined power levels for the range of predetermined power levels. Typically, the control message is a request to vary the output power level for inhibiting radio signal fading.

Abstract: Radio communication apparatus and method for inhibiting radio signal Rayleigh fading comprises apparatus for varying a nominal output power level in accordance with a sequence of power levels. The sequence may be pseudo-random. The nominal output power level may be one of the system power levels inhibiting normal fading and the sequence of power levels varies the output power in a range between adjacent nominal power levels.