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38-403: Snow Hills ( 60°42′S 45°38′W  /  60.700°S 45.633°W  / -60.700; -45.633 ) are two snow-covered hills, one 240 m, the other 265 m and 0.25 nautical miles (0.5 km) to the west. Located 0.2 nautical miles (0.4 km) west of Cemetery Bay in the east-central part of Signy Island . The lower, eastern hill was charted and named "Snow Hill" by DI personnel on

76-400: A scroll chuck . Non-invertible functions, which require the groove to self-intersect, can be implemented using special follower designs. A variant of the face cam provides motion parallel to the axis of cam rotation. A common example is the traditional sash window lock, where the cam is mounted to the top of the lower sash, and the follower is the hook on the upper sash. In this application,

114-405: A cam for the lathe mechanism. A face cam produces motion by using a follower riding on the face of a disk. The most common type has the follower ride in a slot so that the captive follower produces radial motion with positive positioning without the need for a spring or other mechanism to keep the follower in contact with the control surface. A face cam of this type generally has only one slot for

152-497: A constant velocity rise followed by a similar return with a dwell in between as depicted in figure 2. The rise is the motion of the follower away from the cam center, dwell is the motion where the follower is at rest, and return is the motion of the follower toward the cam center. A common type is in the valve actuators in internal combustion engines. Here, the cam profile is commonly symmetric and at rotational speeds generally met with, very high acceleration forces develop. Ideally,

190-402: A convex curve between the onset and maximum position of lift reduces acceleration, but this requires impractically large shaft diameters relative to lift. Thus, in practice, the points at which lift begins and ends mean that a tangent to the base circle appears on the profile. This is continuous with a tangent to the tip circle. In designing the cam, the lift and the dwell angle θ are given. If

228-408: A device that converts rotational motion to reciprocating (or sometimes oscillating) motion. A common example is the camshaft of an automobile , which takes the rotary motion of the engine and converts it into the reciprocating motion necessary to operate the intake and exhaust valves of the cylinders . Cams can be characterized by their displacement diagrams, which reflect the changing position

266-614: A five-wheeled sand-driven clock, artificial paper figurines within a revolving lantern, all utilized cam mechanisms. The Chinese hodometer which utilized a bell and gong mechanism is also a cam, as described in the Song Shi. In the book Nongshu, the vertical wheel of a water-driven wind box is also a cam. Out of these examples, the water-driven pestle and the water driven wind box both have two cam mechanisms inside. Cams that rotated continuously and functioned as integral machine elements were built into Hellenistic water-driven automata from

304-422: A follower being raised over 24 hours by the cam in a spiral path which terminated at a sharp cut off at which the follower would drop down and activate the day advance. Where timing accuracy is required as in clocking-in clocks these were typically ingeniously arranged to have a roller cam follower to raise the drop weight for most of its journey to near its full height, and only for the last portion of its travel for

342-427: A follower on each face. In some applications, a single element, such as a gear, a barrel cam or other rotating element with a flat face, may do duty as a face cam in addition to other purposes. Face cams may provide repetitive motion with a groove that forms a closed curve or may provide function generation with a stopped groove. Cams used for function generation may have grooves that require several revolutions to cover

380-404: A follower would make as the surface of the cam moves in contact with the follower. In the example shown, the cam rotates about an axis. These diagrams relate angular position, usually in degrees, to the radial displacement experienced at that position. Displacement diagrams are traditionally presented as graphs with non-negative values. A simple displacement diagram illustrates the follower motion at

418-633: A group of rocks called the Billie Rocks. The name "Billie Rock", for the easternmost rock of the group, appeared on the 1927 DI chart, and was later extended to include the entire group. North-northwest of the Billie Rocks is Cam Rock, a low ice-worn rock normally visible even at high water. The 1927 DI chart names it for its supposed resemblance to a cam . Just north of Berntsen Point is the descriptively-named Small Rock, charted and named by DI personnel. [REDACTED]  This article incorporates public domain material from websites or documents of

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456-628: A key duplication machine, where the original key acts as a control cam for cutting the new key. Cam mechanisms appeared in China at around 600 BC in the form of a crossbow trigger-mechanism with a cam-shaped swing arm. However, the trigger mechanism did not rotate around its own axis and traditional Chinese technology generally made little use of continuously rotating cams. Nevertheless, later research showed that such cam mechanisms did in fact rotate around its own axis. Likewise, more recent research indicates that cams were used in water-driven trip hammers by

494-399: A plate or block, may be one or more slots or grooves in the face of an element, or may even be a surface profile for a cam with more than one input. The development of a linear cam is similar to, but not identical to, that of a rotating cam. A common example of a linear cam is a key for a pin tumbler lock . The pins act as followers. This behavior is exemplified when the key is duplicated in

532-456: A shaft holding the cam to a set position by pressure from a roller. They were used on early models of Post Office Master clocks to synchronise the clock time with Greenwich Mean Time when the activating follower was pressed onto the cam automatically via a signal from an accurate time source. This type of cam was used for example in mechanical timekeeping clocking-in clocks to drive the day advance mechanism at precisely midnight and consisted of

570-409: A single rotation of the cylinder and generally provide positive positioning, removing the need for a spring or other provision to keep the follower in contact with the control surface. Applications include machine tool drives, such as reciprocating saws, and shift control barrels in sequential transmissions , such as on most modern motorcycles . A special case of this cam is a constant lead , where

608-488: Is Pup Cove, a small cove named by UK-APC in recognition of the first recorded birth of an Antarctic fur seal pup on the island. South of that is the Elephant Flats, a mud flat along the shore frequented by elephant seals , which UK-APC named the feature for. South of Waterpipe Beach is Cemetery Bay, a shallow southwest arm of Borge Bay, lying immediately below Orwell Glacier . UK-APC named it in association with

646-555: Is a flat shingle beach on the west side of Borge Bay. It was named by FIDS in 1947. An old pipe line from a pumping station by Pumphouse Lake, the southernmost lake in Three Lakes Valley , leads down to this beach and was used by the Tonsberg Hvalfangeri for watering whaling vessels between 1920 and 1930. To the southwest are the descriptively-named Marble Knolls, named by UK-APC. The next notable feature

684-432: Is mechanical analog computation and special functions in control systems. A face cam that implements three outputs for a single rotational input is the stereo phonograph , where a relatively constant lead groove guides the stylus and tonearm unit, acting as either a rocker-type (tonearm) or linear (linear tracking turntable) follower, and the stylus alone acting as the follower for two orthogonal outputs to representing

722-553: Is used to deliver pulses of power to a steam hammer , for example, or an eccentric disc or other shape that produces a smooth reciprocating (back and forth) motion in the follower , which is a lever making contact with the cam. A cam timer is similar, and were widely used for electric machine control (an electromechanical timer in a washing machine being a common example) before the advent of inexpensive electronics, microcontrollers , integrated circuits , programmable logic controllers and digital control . The cam can be seen as

760-579: The Discovery II in 1933. In local usage the name Snow Hills has become established for both hills. [REDACTED]  This article incorporates public domain material from "Snow Hills" . Geographic Names Information System . United States Geological Survey .   [REDACTED] This South Orkney Islands location article is a stub . You can help Misplaced Pages by expanding it . Cemetery Bay The headland Balin Point marks

798-752: The Orwell . Right in the inner northwestern corner of the bay are the Mirounga Flats, a small partially enclosed tidal area. The area's eastern limit is formed by the Thule Islands ; its northern and western limits by Signy Island. The tidal area dries at low water. The flats were roughly surveyed in 1933 by DI personnel, and resurveyed in 1947 by FIDS. The feature was named by the FIDS because elephant seals ( Mirounga leonina ) are found there in large numbers during their moulting period. Waterpipe Beach

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836-501: The United States Geological Survey . Cam (mechanism) A cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion. It is often a part of a rotating wheel (e.g. an eccentric wheel) or shaft (e.g. a cylinder with an irregular shape) that strikes a lever at one or more points on its circular path. The cam can be a simple tooth, as

874-414: The audio signals. These motions are in a plane radial to the rotation of the record and at angles of 45 degrees to the plane of the disk (normal to the groove faces). The position of the tonearm was used by some turntables as a control input, such as to turn the unit off or to load the next disk in a stack, but was ignored in simple units. This type of cam, in the form of a symmetric heart, is used to return

912-417: The base (given) and r that of the tip circle (required): The most commonly used cam is the cam plate (also known as disc cam or radial cam ) which is cut out of a piece of flat metal or plate. Here, the follower moves in a plane perpendicular to the axis of rotation of the camshaft. Several key terms are relevant in such a construction of plate cams: base circle , prime circle (with radius equal to

950-409: The cam is used to provide a mechanical advantage in forcing the window shut, and also provides a self-locking action, like some worm gears , due to friction. Face cams may also be used to reference a single output to two inputs, typically where one input is the rotation of the cam and the other is the radial position of the follower. The output is parallel to the axis of the cam. These were once common

988-465: The cam. The output is radial to the cylinder. These were once common for special functions in control systems, such as fire control mechanisms for guns on naval vessels and mechanical analog computers. An example of a cylindrical cam with two inputs is provided by a duplicating lathe , an example of which is the Klotz axe handle lathe, which cuts an axe handle to a form controlled by a pattern acting as

1026-415: The complete function, and in this case, the function generally needs to be invertible so that the groove does not self intersect, and the function output value must differ enough at corresponding rotations that there is sufficient material separating the adjacent groove segments. A common form is the constant lead cam, where the displacement of the follower is linear with rotation, such as the scroll plate in

1064-430: The final portion of the run the profile of the non-roller cam rose more than the other causing the solid follower to take the weight. A linear cam is one in which the cam element moves in a straight line rather than rotates. The cam element is often a plate or block but may be any cross-section. The key feature is that the input is a linear motion rather than rotational. The cam profile may be cut into one or more edges of

1102-739: The latter half of the Western Han Dynasty (206 BC – 8 AD) as recorded in the Huan Zi Xin Lun. Complex pestles were also mentioned in later records such as the Jin Zhu Gong Zan and the Tian Gong Kai Wu, amongst many other records of water-driven pestles. During the Tang dynasty, the wooden clock within the water-driven astronoical device, the spurs inside a water-driven armillary sphere, the automated alarm within

1140-561: The north side of the entrance to Borge Bay. It was charted in 1933 and named in association with Balin Rocks. To the south along the coast are Drying Point, Mooring Point, and Knife Point, whose names first appear on a chart based upon the 1927 survey of Borge Bay, possibly reflecting earlier names given by whalers. Berntsen Point forms the south side of Borge Bay. It was charted in 1927 and probably named for Captain Søren Berntsen of

1178-412: The position of the follower is linear with rotation, as in a lead screw. The purpose and detail of implementation influence whether this application is called a cam or a screw thread, but in some cases, the nomenclature may be ambiguous. Cylindrical cams may also be used to reference an output to two inputs, where one input is the rotation of the cylinder and the other is the position of the follower along

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1216-399: The profile is treated as a large base circle and a small tip circle, joined by a common tangent, giving lift L , the relationship can be calculated, given the angle φ between one tangent and the axis of symmetry ( φ being ⁠ π / 2 ⁠ − ⁠ θ / 2 ⁠ ), while C is the distance between the centres of the circles (required), and R is the radius of

1254-662: The ruins of the whaling factory built in 1920–21 by the Tonsberg Hvalfangeri stand on its southeastern shore. A group of bluffs rising to 120 metres (400 ft) to the south were named Factory Bluffs by UK-APC after the same factory. There are a number of named rocks and rock groups within Borge Bay. The Balin Rocks are a small group of rocks close south of Balin Point, charted and named by Captain Sorlle and Captain Borge. 0.1 nautical miles (0.2 km) northeast of Drying Point are

1292-438: The sum of the follower radius and the base circle radius), pitch curve which is the radial curve traced out by applying the radial displacements away from the prime circle across all angles, and the lobe separation angle ( LSA – the angle between two adjacent intake and exhaust cam lobes). The base circle is the smallest circle that can be drawn to the cam profile. A once common, but now outdated, application of this type of cam

1330-494: The various parts. A cylindrical cam or barrel cam is a cam in which the follower rides on the surface of a cylinder. In the most common type, the follower rides in a groove cut into the surface of a cylinder. These cams are principally used to convert rotational motion to linear motion perpendicular to the rotational axis of the cylinder. A cylinder may have several grooves cut into the surface and drive several followers. Cylindrical cams can provide motions that involve more than

1368-417: The weight to be taken over and supported by a solid follower with a sharp edge. This ensured that the weight dropped at a precise moment, enabling accurate timing. This was achieved by the use of two snail cams mounted coaxially with the roller initially resting on one cam and the final solid follower on the other but not in contact with its cam profile. Thus the roller cam initially carried the weight, until at

1406-435: The whalers' graves on the east side of the feature. Moraine Valley drains north into the Elephant Flats. Between Knife Point and Berntsen Point is Factory Cove, roughly surveyed by Captain Borge. It was originally named Borge Harbour by Captain Sorlle, but that name was later transferred to the overall bay of which this cove forms a small part. The cove was resurveyed by DI personnel in 1927 and renamed Factory Cove, because

1444-480: Was automatic machine tool programming cams. Each tool movement or operation was controlled directly by one or more cams. Instructions for producing programming cams and cam generation data for the most common makes of machine, were included in engineering references well into the modern CNC era. This type of cam is used in many simple electromechanical appliances controllers , such as dishwashers and clothes washing machines, to actuate mechanical switches that control

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