An optical operating fluid detector for optical detection of operating fluid for a hand-guided garden, forestry and/or construction machining appliance includes a light source, an operating fluid line and a light receiver. The light source is designed for radiation of rays of light. The operating fluid line is designed for optical interaction of rays of light from the light source with operating fluid in line for the optical detection of operating fluid. The light receiver is designed for differing reception of rays of light from the line in dependence on the presence or the absence of operating fluid in the line. The operating fluid detector has an optical deflecting device. The deflecting device is designed for deflection of rays of light from the light source to the operating fluid line and/or for deflection of rays of light from the line to the light receiver. The operating fluid line is designed for differing diversion of rays of light from the light source in dependence on the presence or the absence of operating fluid in the line for optical detection of operating fluid.

A grease dispensing device includes a grease drive system for moving grease through grease passaging. A sensor is arranged to sense grease in the grease passaging and to generate sensor data related thereto. After a delay period, a prime indicator changes between first and second states based on the sensor data to indicate whether or not the grease dispensing device is primed with grease. The grease dispensing device also includes a grease controller operatively connected to the sensor and the prime indicator. The grease dispensing device monitors the sensor data to determine whether the grease dispensing device is primed with grease and controls the operation of the prime indicator accordingly. The grease controller includes a tangible storage medium which stores executable instructions to change the state of the prime indicator based on the sensor data and to delay changing the state of the prime indicator for the delay period after the controller determines the grease dispensing device is not primed with grease.

A grease dispensing device includes a grease drive system for moving grease through grease passaging. A sensor is arranged to sense grease in the grease passaging and to generate sensor data related thereto. After a delay period, a prime indicator changes between first and second states based on the sensor data to indicate whether or not the grease dispensing device is primed with grease. The grease dispensing device also includes a grease controller operatively connected to the sensor and the prime indicator. The grease dispensing device monitors the sensor data to determine whether the grease dispensing device is primed with grease and controls the operation of the prime indicator accordingly. The grease controller includes a tangible storage medium which stores executable instructions to change the state of the prime indicator based on the sensor data and to delay changing the state of the prime indicator for the delay period after the controller determines the grease dispensing device is not primed with grease.

A method for evaluating the lubrication of friction components of an apparatus which can be lubricated by means of a lubricant circuit. A lubricant pump of the lubricant circuit is drivable by a drive engine. A pressure ascertainment unit continuously ascertains the lubricant pressure at at least one defined region of the lubricant circuit during an engine start procedure. A travel ascertainment unit is provided, by means of which at multiple pressure points in time, at each of which the lubricant pressure ascertained exceeds a defined pressure limiting value (p.sub.1, p.sub.2, p.sub.3), the relative travel between the friction components since the beginning of the engine start procedure is ascertained or estimated, and an analysis unit, by means of which an evaluation value, is ascertained from the total of the relative travel values (.sub.1, .sub.2, .sub.3) ascertained at the pressure points in time.

An optical operating fluid detector for optical detection of operating fluid for a hand-guided garden, forestry and/or construction machining appliance includes a light source, an operating fluid line and a light receiver. The light source is designed for radiation of rays of light. The operating fluid line is designed for optical interaction of rays of light from the light source with operating fluid in line for the optical detection of operating fluid. The light receiver is designed for differing reception of rays of light from the line in dependence on the presence or the absence of operating fluid in the line. The operating fluid detector has an optical deflecting device. The deflecting device is designed for deflection of rays of light from the light source to the operating fluid line and/or for deflection of rays of light from the line to the light receiver. The operating fluid line is designed for differing diversion of rays of light from the light source in dependence on the presence or the absence of operating fluid in the line for optical detection of operating fluid.

Herein provided are methods and systems for detecting blockage of an inlet of gas turbine engine. An oil temperature measurement of the engine and an ambient temperature measurement is obtained. The oil temperature measurement is compared to a threshold based on the ambient temperature measurement. Blockage of the inlet of the engine is detected when the oil temperature measurement exceeds the threshold.

A method for evaluating the lubrication of friction components of an apparatus which can be lubricated by means of a lubricant circuit. A lubricant pump of the lubricant circuit is drivable by a drive engine. A pressure ascertainment unit continuously ascertains the lubricant pressure at at least one defined region of the lubricant circuit during an engine start procedure. A travel ascertainment unit is provided, by means of which at multiple pressure points in time, at each of which the lubricant pressure ascertained exceeds a defined pressure limiting value (p.sub.1, p.sub.2, p.sub.3), the relative travel between the friction components since the beginning of the engine start procedure is ascertained or estimated, and an analysis unit, by means of which an evaluation value, is ascertained from the total of the relative travel values (.sub.1, .sub.2, .sub.3) ascertained at the pressure points in time.

The present disclosure relates to a lubrication monitoring system (15) configured to monitor a supply of lubricant in a hand-held cutting tool (1) having a cutting unit (3, 5). A lubricant tank (41) and a conduit (45) are configured to duct a flow of lubricant from the tank (41) to the cutting unit (3, 5). The lubrication monitoring system (15) comprises a heating element (29) and a sensor arrangement (31, 33), the heating element (29) being configured to heat the lubricant flow. The sensor arrangement comprises a first sensor (31) located at the flow, upstream of the heating element (29), and a second sensor (33) located at said flow, downstream of the heating element. The lubrication monitoring system outputs a monitoring signal based on a sensed temperature difference between the first and second sensors (31, 33).