Abstract: A needle guard (1) based upon a canting plate (6) becomes lockingly engaged with the needle (2) shaft both upon retraction of the needle tip within the guard (1), and upon any attempt to cause the needle tip to reemerge from the guard (1). The plate (6) is positioned to rotate into locking engagement with the shaft of the needle (2) both when an attempt is made to further withdraw the needle from the needle guard (1) and when an attempt is made to cause the needle tip to reemerge from the needle guard (1).

Abstract: A needle tip protecting device is provided for hypodermic needles, catheters and the like. The device is small enough to be stored at the base of the needle prior to and during use. After use it may be slid to cover the needle tip where it automatically self-attaches and becomes non-removable. Embodiments of mechanisms which achieve this effect by means of a tapered cavity, collet or angled jamming surface are described.

Abstract: A needle tip protecting device is provided for catheters having an insertion needle. The device is small enough to be stored at the base of the catheter needle prior to and during use. After use it may be slip to cover the needle tip where it automatically self-attaches and becomes non-removable. Various embodiments of mechanisms to achieve this effect are described.

Abstract: An automatic needle guard for intravenous catheter assemblies, which stores on the insertion needle between the needle base and catheter hub, which attaches by positive engagement to the catheter hub, remains attached while the needle is withdrawn through the needle guard following insertion of the catheter, locks immovably to the needle shaft when the needle tip enters the body of the needle guard, then releases from the catheter hub, allowing the needle guard to be withdrawn along with the needle for safe disposal.

Abstract: A needle tip protecting device is provided for catheters having an insertion needle. The device is small enough to be stored at the base of the catheter needle prior to and during use. After use it may be slip to cover the needle tip where it automatically self-attaches and becomes non-removable. Various embodiments of mechanisms to achieve this effect are described.

Abstract: A needle tip protecting device is provided for hypodermic needles, catheters, and the like. The device is small enough to be stored at the base of the needle prior to and during use. After use it may be slid to cover the needle tip where it automatically self-attaches and becomes non-removable. Various embodiments of mechanisms to achieve this effect are described.

Abstract: In a distribution circuit for connecting a load to an a-c source, it is known that a ground-to-neutral short tends to reduce the sensitivity of ground fault detectors that use a differential current transformer to sense line-to-ground leakage. A resonated coil on a core links the neutral conductor forming part of a protective device for interrupting the load circuit in the event of reduced Q of the resonated coil caused by a neutral-to-ground fault. The core must also link the line conductor, for otherwise a loop including the line, the load and the neutral would wrongly have a like effect.The same core and coil are used with a common amplifier for the neutral-to-ground fault detector and for the line-to-ground leakage detector, so that the apparatus can be economical and compact. Furthermore, so long as there is no neutral-to-ground fault, the amplifier delivers a signal of normal strength that monitors the integrity of both detectors.