A calibration block dimensioned and adapted to set a consistent, repeatable furrow depth for planter units. The calibration block provides a deck with a slot for receiving a first plate for supporting a distal end of the planter unit when setting its gauge wheels, whereby the first plate is flush with the deck at a predefine distance from the soil. The calibration block also provides a gauge block and associated second plate for increasing the predefined distance, if the user so desires.

A calibration block dimensioned and adapted to set a consistent, repeatable furrow depth for planter units. The calibration block provides a deck with a slot for receiving a first plate for supporting a distal end of the planter unit when setting its gauge wheels, whereby the first plate is flush with the deck at a predefine distance from the soil. The calibration block also provides a gauge block and associated second plate for increasing the predefined distance, if the user so desires.

A method is provided for measuring the milling depth of a road milling machine, the machine being operative to mill a ground surface with a milling roller lowered to a milling depth to create a milling track, the machine including at least one side plate located to at least one side of the milling roller to engage an untreated ground surface, and the machine including a stripping plate operative to be lowered onto the milling track generated by the milling roller. The method includes measuring the milling depth of the milling track, the measuring including detecting a measurement value of a ground engaging sensor engaging the milling track.

A method is provided for measuring the milling depth of a road milling machine, the machine being operative to mill a ground surface with a milling roller lowered to a milling depth to create a milling track, the machine including at least one side plate located to at least one side of the milling roller to engage an untreated ground surface, and the machine including a stripping plate operative to be lowered onto the milling track generated by the milling roller. The method includes measuring the milling depth of the milling track, the measuring including detecting a measurement value of a ground engaging sensor engaging the milling track.

The invention relates to a ground milling machine, comprising: a machine frame supported by front and rear travel units and at least partially height-adjustable; a milling drum housing arranged on the machine frame, comprising a milling drum that is rotatable about a horizontal axis of rotation perpendicular to the milling direction; a retaining device arranged in front of the milling drum housing in the milling direction with an adjustment device that enables the height adjustment of the retaining device in relation to the milling drum housing and the machine frame; and a ground contact device arranged in front of the milling drum housing in the milling direction with a contact runner and a mounting lever. The contact runner is adjustable in relation to the retaining device within a height-adjustment range and is mounted on the retaining device by way of the mounting lever. The contact runner comprises a first joint via which it is connected to the mounting lever in a pivotable fashion, the mounting lever being connected to the retaining device via a second joint and positioned between the contact runner and the retaining device in such a manner that, when the height of the retaining device is adjusted in relation to the contact runner, the mounting lever reaches or traverses an apex of the curve of movement of the mounting lever about the first or second joint, the apex delimiting the adjustment path of the mounting lever in the horizontal direction over the entire height-adjustment range, in particular in such a manner that the horizontal distance between the first and the second joint increases before subsequently decreasing. Finally, a distance measuring device is provided, with which the vertical distance or a correlating value between the machine frame and/or the milling drum housing and the contact runner can be measured.

Indoors positioning and navigation systems and methods are described herein. In one embodiment, a system for inspecting or maintaining a storage tank includes a vehicle having: at least one sensor for determining properties of a storage tank and a navigation system. The navigation system includes an acoustic transmitter carried by the vehicle and an inertial measurement unit (IMU) sensor configured to at least partially determine a location of the vehicle with respect to the storage tank. The vehicle also includes a propulsion unit configured to move the vehicle within the storage tank, and an acoustic receiver fixed with respect to the storage tank. The vehicle moves inside the storage tank in concentric arcs with respect to the acoustic receiver.

Indoors positioning and navigation systems and methods are described herein. In one embodiment, a system for inspecting or maintaining a storage tank includes a vehicle having: at least one sensor for determining properties of a storage tank and a navigation system. The navigation system includes an acoustic transmitter carried by the vehicle and an inertial measurement unit (IMU) sensor configured to at least partially determine a location of the vehicle with respect to the storage tank. The vehicle also includes a propulsion unit configured to move the vehicle within the storage tank, and an acoustic receiver fixed with respect to the storage tank. The vehicle moves inside the storage tank in concentric arcs with respect to the acoustic receiver.

A machining tool assembly for manufacturing a firearm lower receiver includes a first and second side jig which are configured to be disposed on opposite sides of the firearm lower receiver and configured to removably attach to one another securing the firearm lower receiver therebetween. A drill block jig is removably attachable to the first and second side jigs disposed above the top surface of the firearm lower receiver, wherein the drill block jig has at least one through hole. A router support plate is disposed above and removably attachable to the first and second side jigs. A router aperture is disposed through a router support plate thickness.

A machining tool assembly for manufacturing a firearm lower receiver includes a first and second side jig which are configured to be disposed on opposite sides of the firearm lower receiver and configured to removably attach to one another securing the firearm lower receiver therebetween. A drill block jig is removably attachable to the first and second side jigs disposed above the top surface of the firearm lower receiver, wherein the drill block jig has at least one through hole. A router support plate is disposed above and removably attachable to the first and second side jigs. A router aperture is disposed through a router support plate thickness.

Indoors positioning and navigation systems and methods are described herein. In one embodiment, a system for inspecting or maintaining a storage tank includes a vehicle having: at least one sensor for determining properties of a storage tank and a navigation system. The navigation system includes an acoustic transmitter carried by the vehicle and an inertial measurement unit (IMU) sensor configured to at least partially determine a location of the vehicle with respect to the storage tank. The vehicle also includes a propulsion unit configured to move the vehicle within the storage tank, and an acoustic receiver fixed with respect to the storage tank. The vehicle moves inside the storage tank in concentric arcs with respect to the acoustic receiver.