Abstract: A longitudinally displaceable column includes a longitudinal adjusting unit which is supported on a base plate of a vertical tube. The adjusting unit has a rod that receives an axial bearing, which is interposed between the rod and the base plate so that the rod is rotatable relative to the base plate. The axial bearing is a sliding bearing that has a sliding member.

Abstract: An adjustable suspension for a vehicle seat mounted on a scissors linkage wherein the spring supporting suspension force may be adjustable over a wide range of user weight, and wherein the scissors linkage permits the seat, which may include a back, to move in a substantially vertical direction during seat suspension movement.

Abstract: A height adjustable pedestal comprises a base, a height adjustment column disposed above the base and supported thereon, and a table top or chair seat support disposed above the height adjustment column. The height adjustment column comprises at least two spring actuated telescoping height adjustment mechanisms. The height adjustment column typically additionally includes at least one stand tube each having a first and a second end. The first end includes an opening or hole through which a telescoping height adjustment mechanism passes. The second end of each stand tube is proximate to the base. At least one support, disposed vertically above or below the base of the pedestal, for securing the stand tubes together, may also be included. Telescoping height adjustment mechanisms used in the pedestal are typically gas springs. Supports for securing the stand tubes together may comprise a platform. Such platforms include attachment means to attach the platform to the base.

Abstract: A non-swiveling height adjustable work chair comprises a seat, a base, and a non-swiveling height adjustment column disposed intermediate the base and the seat. The height adjustment column comprises at least two telescoping height adjustment mechanisms, wherein the telescoping height adjustment mechanisms secure the seat against rotation in relation to the chair base. The chair additionally comprises a lever to actuate the height adjustment mechanisms. The height adjustment column may typically comprise a single stand tube having a first and a second end, wherein the first end is attached to the chair base and extends vertically therefrom, and the second end includes at least two holes through which the telescoping height adjustment mechanisms pass.

Abstract: The disclosure relates to a vertically operating linear actuator for a multi-stage extendible column for carrying a cinematograph or TV camera. A load representing the weight imposed by the multi-stage column with its camera is indicated at (10), a vertically extending gas strut at (11) and a base (12). A piston rod (15) of the strut carries a rotatable disc mounted on a pivot pin eccentrically to its geometric center to provide a varying radius of rotation between the offset center and disc periphery (21). A tether (22) extends over the disc and is secured at one end to an anchorage (23) on the base and the other end supports the load (10). The effective force applied by the strut to the weight (10) will be determined by the effective radii of the disc (20) at points where the tether engages the disc.

Abstract: Adjustable-height column, especially for chairs, includes a guide tube and a pneumatic, selectively blockable piston-cylinder unit for height adjustment located in the guide tube. The piston sealingly subdivides the cylinder into two operational chambers. Beginning at a defined retracted setting of the piston-cylinder unit, the blocking function is compulsorily canceled, in that a fluid flow connection between the two operational spaces is established which overrides the blocking function. An additional spring element is placed in series with the piston-cylinder unit to prevent a sudden collapse of the column.

Abstract: A pedestal assembly for a boat seat is disclosed which combines in a single lever adjustment the ability to raise and lower the seat as well as to lock or unlock the seat to permit clockwise and counterclockwise swivel action. The lever is pulled up for vertical adjustments up or down. The lever is pushed down facilitating clockwise or counterclockwise pivoting about the pedestal of the seat. When the lever is released it is spring-biased to a neutral position. Depending on the configuration, the seat can be locked in one or more swivelled positions about the pedestal. The seat can be easily detached from the pedestal through a mechanism which remains on the seat mount so that it will not be lost in the boat or overboard. The detachment pin assembly also provides positive feedback that the seat has been properly secured to the pedestal and locked.

Abstract: The hydraulic device for raising and lowering seat of the barber's chair has a main housing section and a lower section. A sliding plunger is slidably mounted in a sleeve extending between the lower section and the top cover of the main housing section. An oil pump is operative to force the oil contained with the main housing section into a channel in the lower section to the bottom of the sleeve for raising or lowering the sliding plunger. The seat of the barber's chair is mounted to the top of the sliding plunger. The joint between the lower section and the main housing section is permanently sealed with a metal compound by welding, brazing or soldering.

Abstract: A height-adjustable column has a stationary tube that receives a height-changing mechanism, such as a pneumatic spring having a cylinder and a rod that are axially movable with respect to one another. A transmitting mechanism includes a movable member that is operatively associated with the rod and is movable in a direction opposite to the direction of movement of the cylinder upon extension of the pneumatic spring when the pneumatic spring is in a predetermined lift zone.

Abstract: A split sleeve bushing for providing a tight fit between a support post and chair base comprises two hemi-cylindrical components which mount about the support post and are received within the support post receptacle of the chair base. The split sleeve bushing includes external stability rings and vertical ribs extending along the external surface thereof. The vertical ribs are tapered to match the draft angle of the support post receptacle of the chair base. The upper end of the split sleeve bushing includes a circumferential flange which is slotted for snap lock engagement with the chair base.

Abstract: A vertically adjustable column, in particular for chairs or tables, includes a pedestal tube having a coaxially arranged lengthwise adjusting element, e.g., a gas spring, and a rotational fixation profile engaging a counterpart profile extending parallel to the longitudinal centerline of the pedestal tube. The rotational fixation profile and the counterpart profile are operatively arranged between the pedestal tube and the lengthwise adjusting element, and one of the profile parts is arranged in series with the lengthwise adjusting element.

Abstract: A seat height adjustment system particularly adapted for use with vehicle seats and which permits the elevation of one side of the seat base to be adjusted relative to the elevation of an opposite side of that base. The system employs spring assemblies to provide an upwardly directed bias on the seat base which urges that base towards a position of maximum elevation. An actuator is operable to effect downward adjustment of the seat base elevation by imposing a force on the seat base which acts counter to the bias force. Actuator may include two electric motors each of which is connected to a respective two corners of the seat base through flexible drive cables. The arrangement is such that the seat base corners controlled by a respective one of the motors move up or down according to whether the motor is operated in a forward or a reverse mode respectively.

Abstract: An improved adjustable armrest for use on a chair is particularly related to an adjustable armrest in connection to a pneumatically operated cylinder permitting the armrest body to be vertically lifted up by actuation of a control stick or lowered down by a manual force against the armrest body. An armrest mount having tracks defined thereon for mounting of the armrest body permits the armrest to be slidably adjusted back and forth. The armrest mount with the armrest body is secured to a housing having a vertical hole for receiving the cylinder having one end engaged with the underside of a bottom bracket which is secured to the armrest mount. The cylinder housed in a tubular sleeve is fixed at the bottom end thereof to a support bracket and is engaged with a hand operated stick at the top end so that the actuation of the control stick results in the extension of the cylinder and the armrest body accordingly.

Abstract: A shock-absorbing and height-adjusting assembly for mounting a seat onto the seat-supporting framework tubing of a bicycle frame. A standard, commercially available, adjustable-length gas spring (hydropneumatic spring), of the type used for the control column of adjustable height chairs, is slideably contained within a hollow receiver attached alongside or within a lower portion of the bicycle seat supporting framework to which the gas spring piston rod is affixed with the upper end of the gas spring in underlying contact with the lower end of a vertically extending elongated cylindrical seat supporting guide tube supported in alignment with the gas spring for axial and non-rotational movement within a bushing assembly affixed to the uppermost portion of the bicycle seat supporting framework.

Abstract: A new automatic bicycle seat adjuster for adjusting a bicycle seat's height while riding. The inventive device includes a support tube slidably receivable within an existing seat support tube of a bicycle frame. The support tube has a generally elongated and cylindrical configuration with an open upper end and a closed lower end. A gas cylinder is received within the support tube. The gas cylinder has a lower end secured to the closed lower end of the support tube. The gas cylinder has a release valve extending upwardly from an upper end thereof with the release valve positioned outwardly of the open upper end of the support tube. A bicycle seat is adjustably secured with respect to the gas cylinder. A release lever is coupled with respect to the release valve of the gas cylinder.

Abstract: A camera pedestal has a cylinder with a tapering cross-section for providing a uniform counterbalancing force using a compressed gas. Telescoping column sections which make up a column assembly have inner relief channels and outer slots for hardened roller strips. A column drive system has a hydraulic actuator to remotely raise the column assembly, and to lock the column assembly into any selected position. The column assembly is eccentrically positioned on its base tank. The pedestal is engageable to a receptacle on a camera dolly with a telescoping steering drive tube interconnecting a steering assembly on the pedestal with a steering system in the dolly.

Abstract: A furniture system includes a table comprising a base adapted to stably engage a floor, and a table top assembly including a table top. The table includes a gas-spring-operated lift assist operably connected to the base and the table top assembly for selectively lifting/lowering the table top. An actuator button is positioned in a center of the table top and is operably connected to a release button for operating the lift assist. The table top can be operated by one hand by pressing downwardly on the button just hard enough to release the gas spring but not hard enough to push the table top downwardly, whereby the gas spring raises the table top. Alternatively, the user can press downwardly hard enough to both release the gas spring and force the table top downwardly against the force of the gas spring. The furniture system also includes a chair with an articulatable tablet adapted to interface with the table.

Abstract: A vertically adjustable column for supporting a seat of a chair. The column includes an outer guide tube mounted to a support stand, an intermediate telescoping tube slidably positioned with the guide tube and an inner telescoping tube slidably positioned within the intermediate tube. An upper portion of the inner telescoping tube is connected to the seat. A gas spring includes a cylinder mounted within the inner tube, a piston rod extending outwardly from the cylinder and a control pin assembly mounted to an upper portion of the cylinder. The piston rod is connected to the guide tube and is extensible between a collapsed position in which the cylinder and inner tube are substantially within the intermediate tube and the intermediate tube is substantially within the guide tube, and a raised position in which a portion of the cylinder and inner tube extend outwardly from the intermediate tube and a portion of the intermediate tube extends outwardly from the outer guide tube.

Abstract: A pneumatic height adjustment column is provided for a chair. The column includes a support tube, a carrier tube, a pneumatic cartridge, a hub fastener, and a shaft fastener. The support tube has a top end which is generally open, and a bottom portion which is adapted to be mounted to a chair base. The bottom portion has an opening with a smaller diameter than that of the support tube. The carrier tube has a top portion adapted to be mounted to a support housing for a chair seat. The top portion has an opening with a smaller diameter than that of the carrier tube. The carrier tube also has a generally open bottom end which telescopically engages the top end of the support tube. The pneumatic cartridge has a cylinder positioned within the carrier tube, a shaft, and a hub. The cylinder has a diameter greater than that of the opening in the carrier tube. The shaft extends downwardly from the cylinder and has a bottom end which passes through the opening in the bottom of the support tube.

Abstract: The disclosure relates to a camera mounting (11) providing a number of axes of movement for a camera supported on the mounting with a motor drive for each axis. A manually operable control system is provided for the motorized drives having a control member (16) and means operable in response to forces applied manually to the control member in the direction of the respective axes to energize the corresponding motor drive or drives for the mounting to produce movement of the mounting proportional to the force applied in the or each axis.

Abstract: A pneumatic cylinder for use in a pneumatic lever-lift chair, including a cylindrical casing having an inward bottom flange and a plurality of vertically spaced inside annular flanges, a stop plate mounted inside the cylindrical casing and having a plurality of raised portions at the bottom respectively welded to the inward bottom flange of the cylindrical casing by a spot welding machine, and an inner barrel mounted inside the cylindrical casing and having an outward top flange stopped above the top end of the cylindrical casing and a plurality of vertically spaced annular grooves around the periphery respectively forced into engagement with the inside annular flanges of the cylindrical casing.

Abstract: A mounting system comprising an adjustment means adaptable for assuming a load, a supporting member and a bearing member in spaced relationship, and a compressible resilient member is disposed in supporting relationship with the bearing member. A portable fluidic cylinder is adaptable for connection and disconnection to a fluid source means, and an opening between the bearing member and the supporting member, such as an opening in a side wall of the supporting member, is of sufficient size to accommodate the cylinder. The fluidic cylinder is portable and adaptable for interposition between the bearing member and the supporting member and extendable to space the supporting member in a direction away from the bearing member without reducing deflection or compression of the resilient member, thereby permitting adjustment of extremely heavy loads.

Abstract: An adjustable basketball goal generally includes a movable support, telescoped within a vertically mounted fixed support, and a hydraulic, water-powered drive mechanism for enabling the raising or lowering of a basketball rim connected to the upper end of the movable support. The drive mechanism includes a dual-compartment water piston and is powered by a conventional garden hose using ordinary household water pressure. With appropriate adjustments made to the water piston, the drive mechanism may be alternatively operable by pneumatic pressure as well as hydraulic pressure. A valve is included for enabling manual control of the drive mechanism. The adjustable basketball goal may also include a rotatable coupling between the movable and fixed supports such that the basketball rim may be rotated 360 degrees about an axis defined by the vertically mounted supports.

Abstract: An adjustable-length column for chairs or the like has an upright tube and a pneumatic or hydropneumatic length-adjusting element arranged in the latter, the housing of the element being radially supported in the upright tube and displaceably guided in the direction of a common axis. A profile guarding against twisting is tightly arranged on the housing in particular by shrinking and has at least one radially projecting web which extends parallel to the axis and engages with a groove-like recess of a guide which is non-rotatably connected with the upright tube.

Abstract: A camera pedestal has a cylinder with a tapering cross-section for providing a uniform counterbalancing force using a compressed gas. Telescoping column sections which make up a column assembly have inner relief channels and outer slots for hardened roller strips. A column drive system has a hydraulic actuator to remotely raise the column assembly, and to lock the column assembly into any selected position. The column assembly is eccentrically positioned on its base tank. The pedestal is engageable to a receptacle on a camera dolly with a telescoping steering drive tube interconnecting a steering assembly on the pedestal with a steering system in the dolly.

Abstract: A multi-functional table with elevational capabilities comprising a base in a generally rectangular configuration having an upper surface and a parallel lower surface; a table top in a generally rectangular configuration having an upper surface and a parallel lower surface; a central cylindrical support having an upper end secured to the lower surface of the table top and having a lower end secured to the upper surface of the base, the support being formed of a tubular member of an enlarged diameter at the lower end and a tubular member of a reduced diameter at the upper end for being slidably received within the lower component; a pump including a foot pedal secured to the base adjacent to the lower component whereby reciprocation of the foot pedal will act to supply air to the space between the upper and lower components to thereby raise the upper component and the working level of the table; and a plurality of apertures formed in the table top and supplemental components adapted to be secured to the table

Abstract: A telescopically extensible lifting column, particularly for the height adjustment of a camera, consists of an external column member resting on a base plate, a middle column member which is telescopically extensible from the external column member, and a central column which is extensible from the middle column member and on which the camera can be mounted. By means of a piston/cylinder type drive device, the middle column member can be pressurized pneumatically in relation to the stationary external column member. The drive device also has a traction cable which is wound or a deflection member mounted rotatably on the middle column member. The cable is connected by means of its inner end portion to the central column member and by means of its outer end portion to the external column member.

Abstract: A cylinder of adjustable length comprises a cylinder body, two pistons slidable in the cylinder body, and a rod which is connected to both pistons and projects from one end of the cylinder body. A dividing wall forming part of the cylinder body defines a first chamber which faces one of the pistons and a second chamber which is separate from the first chamber and in which the other piston is slidable. The two chambers are filled with a fluid, preferably grease, and communicate with each other through a duct controlled by a remotely-controllable valve. The rod and the cylinder body can be locked in any relative position by the closure of the valve to prevent the passage of the fluid from one chamber to the other.

Abstract: An elevation mechanism of a tripod in which a vertical column having a universal head fixed at its upper end is elevationally journalled within a thrust bearing hole bored within a metal fitting base by means of a lifting mechanism of the rack and pinion type and within which is journalled one end portion of three standard legs of a tipod which are equally disposed about the periphery thereof and which are pivotable with respect thereto the improved elevation mechanism of the tripod in which the vertical column comprises an aluminum tubing, and a rack member molded as a separate member with respect to the column from a suitable synthetic resin and which is formed with a rack gear is integrated within one side of the vertical column along the axial direction thereof, while a pinion gear is rotatably supported within the metal fitting base so as to be meshed with the rack gear.

Abstract: The invention relates to an upright positioning structure with a pushing bar applying the upright positioning and pushing effort to the sub femoral area (3) and more particularly the ischial-femoral angle (3) of the user, pressing against the ischial projections of the user's pelvis and providing a resistance to forward sliding during the lifting up movement, the buttock and lumbar region of the user remaining outside of the pushing bar and unsupported.This structure is particularly applied to armchairs or fixed or mobile seats.

Abstract: An adjustable switchboard desk has a top which can be raised and lowered by at least two telescopic legs. In each telescopic leg a hydraulic cylinder and its associated piston are arranged. The cylinder is fixed to the desk-top and the piston is fixed to an outer part of the telescopic leg, or vice versa. The inner and outer parts of the respective telescopic legs are made of closed profile with longitudinally extending, mutually co-acting guide surfaces.

Abstract: A taper connection between a chair column and a seat plate is proposed. The external taper of the chair column adjoins a cylindrical section of the chair column. The internal taper of the seat plate, fitted together with the external taper of the chair column, protrudes beyond the transition between cylindrical section and external taper.

Abstract: An adjustable height stand for a visual display unit incorporates a column adjustably mounted within a base part, with a gear train for effecting vertical adjustment. The gear train incorporates a helical gear arranged with its axis in parallel with the column, and cooperates with a gear part mounted to the column. The helical gear may be rotated by a hand wheel through a gear train incorporating a pair of meshing bevel gears. Alternatively, the helical gear may be driven by a motor. The stand is rotatable relative to the work surface about a vertical axis, and the visual display unit is tiltable relative to the support. The spring is provided for compensating for the weight of the visual display unit.

Abstract: Mechanism for raising/lowering a seat structure. A motor-operated screw-nut assembly is operatively connected to the seat structure via a lazy tongs support system. Laterally spaced guide devices give the support system a desired wide-stance stability that prevents undesired lateral dislocation of the seat structure. The support mechanism is compactly arranged beneath the seat structure, whereby the assembly is adapted to be used in military vehicles.

Abstract: A piece of boat furniture is vertically adjustable by a pneumatically controlled system. The furniture includes a base securely mountable to the deck of a boat. A first hollow shaft of generally square cross section is secured to the base and extends upwardly therefrom. A second hollow shaft of generally square cross section is longitudinally movable with respect to the first shaft. The shafts are coaxial, with one of the shafts disposed at least partially inside the other. The spacing between the shafts is sufficiently small that the shafts cannot twist or rotate with respect to each other. A fluid operated piston is operably secured to the second shaft for moving it longitudinally with respect to the first shaft. A mounting surface is disposed at the top of the second shaft and fixedly secured thereto. A seat, table top or the like is secured to the mounting surface.

Abstract: A chair back height adjustment mechanism for a chair having a chair back supporting standard and a chair back bracket with a chair back or backrest mounted thereon includes a rack gear on the chair back standard, a pinion gear supported in a bearing on the chair back bracket, a worm gear coaxial with the pinion gear, and worm threads on a dial shaft supported on the bracket. Rotation of the dial causes the worm member to rotate the worm gear and the pinion gear whereby the bracket supporting the pinion gear is translated in relation to the chair back standard. The chair back can only be adjusted by operation of the dial due to the nature of the worm and worm gear combination, thus preventing changes in the adjusted position of the chair back by contact with the chair back.

Abstract: A pedestal-type chair having a height-adjusting air spring connected between the base and seat assemblies, and a manually activated control for releasing the air spring. The control includes a small manually engageable activating lever pivotally supported interiorly of the seat assembly adjacent one side thereof and positioned so as to project slightly downwardly a small extent through the lower seat shell. This lever is connected to one end of an elongated flexible cable which extends interiorly of the seat assembly and has its other end connected to a force transfer lever positioned within the central interior of the seat assembly. This latter lever activates the valve-release member associated with the air spring.

Abstract: A hydraulic lifting mechanism for an article of furniture including a refrigerant containing reservoir. The mechanism includes a flexible bag having a variable volume and fixed volume reservoir including a diaphragm for dividing the reservoir into two chambers. The first chamber contains hydraulic liquid and the second chamber contains a compressed two phase working fluid. The hydraulic liquid may be transferred between the flexible bag and the first chamber. A control valve mechanism is included in the flexible conduit which connects the flexible bag with the first chamber. The mechanism may be used in combination with a chair to provide an adjustable height control for the seat of the chair or in combination with other articles of furniture.

Abstract: A gas spring for height adjustment of drawing-tables or the like includes an arrangement for hydraulically locking the gas spring against sudden collapse due to overloading or loss of internal gas pressure. The hydraulic locking mechanism includes a pressure responsive valve which operates, in response to an excess pressure differential between the gas spring cavity and the pressurized gas chamber, either to prevent flow of the hydraulic locking medium out of the cylinder cavity or to restrict such flow to a slow, safe rate.

Abstract: This invention is a foldable basketball goal means having a plurality of basketball goal assemblies, namely two or four counterbalanced units, which are individually movable from a usage position to a folded position and being lowered from an elevated usage position for movement through conventional gymnasium door structures. More particularly, the foldable basketball goal means includes a basketball goal means; a goal support means having one end connected to the basketball goal means; a base support means connected to a lower end of the goal support means in order to raise and lower the basketball goal means. The main base support means includes an actuator wheel assembly which acts automatically on raising and lowering of the basketball goal means to anchor the main base support means in the usage condition or raise the main base support means for lateral movement in all directions of the entire invention to a desired location.

Abstract: A structural support arrangement in which an inner pipe member is telescopically movable within an outer pipe member. The telescopic members have cross-sections of rectangular and/or square pipes. A self-actuated drive roller is held in elongated holes which are inclined to an axis of the support. The drive roller is knurled or has a roughened surface which abuts against the inner pipe member. The inner pipe member, furthermore, is grasped from behind by a roll bearing member which also serves as a back counter bearing for the drive roller. At least one supporting roller may be arranged with divided parts and extend over the width of the inner pipe member. A traverse member on the outer pipe member is movable about a vertical axis and retains a roller holder which extends between the divided portions of the supporting roller.

Abstract: A pneumatically adjustable pedestal for a boat seat comprising an assembly of telescoping sections, the assembly comprising a cup-shaped base section adapted to be inset in an opening in a deck of a boat and having a flange bearing on the floor around the opening, and intermediate sections and an upper end section adapted pneumatically to be raised and lowered, the upper end section being adapted for mounting a boat seat at its upper end, each successive section from the top down being retractable into the next section below, whereby the seat may be lowered to a level adjacent the deck, the sections being pneumatically upwardly extensible.

Abstract: Lowering and hoisting apparatus for high mast luminaires. Luminaire support ring is mounted for movement along a hollow pole by a plurality of hoist cables secured at one end to a transition plate which is located inside the pole and to which is also attached a winch cable operated by a winch at the base of the pole for raising and lowering the support ring. Both the hoist cables and the winch cable are secured to the transition plate by freely rotatable ball bearing devices to prevent the cables from twisting and tangling during the raising and lowering operations.

Abstract: A medical stool with a seat the vertical location of which may be varied by the user through telescopic extension and retraction of tubular members comprising a post assembly selectively relatively displaced by the weight of the user and pressure from within a tank disposed beneath the stool seat as controlled by a valve assembly situated centrally interior of the tank and manually actuated from time to time as desired using a lever located beneath the seat.

Abstract: A column in which an inner elongated member of circular cross section is partly received in the polygonal bore of an outer, tubular member and secured against angular displacement about the common axis by guide elements secured against longitudinal movement in respective recesses of the inner member open toward the outer member and engaging the outer member in respective corners of its polygonal cross section. A manually controlled arresting mechanism permits the two column members to be arrested against relative longitudinal movement in a multiplicity of relative positions.

Abstract: A height-adjustable chair or table pedestal having a hydraulically lifting cylinder and a piston rod telescopically extending therefrom is characterized by having the lower end of the piston rod mounted in the base of the device, with an energy source, hydraulic pump means and a lifting mechanism mounted as a sub-assembly out of view on the underface of the chair or table.

Abstract: An adjustable gas cylinder control comprising the combination of a single tube defining a single cylinder bore, a single piston slidable in the tube and dividing the tube into a first and a second compartment, a first and a second end plug adapted to sealably fit within the ends of the tube, a single spindle or rod fixedly mounted to the piston and reciprocable in the tube, gas inlet means for charging the sealed first compartment of the tube with gas, and valve means mounted in the piston and spindle for allowing gas flow between the first and second compartments of the tube thereby adjusting the position of the piston in the tube. The tube itself is made of rolled welded sheet metal with its ends having a simple cold formed impression holding the first and second end plugs. Also provided is actuating means including a lever connected to the spindle for actuating the valve means thereby allowing gas flow between the compartments of the tube.

Abstract: A vertically-oriented hydraulic cylinder has its piston rod attached to a pulpit or a lectern that is vertically guided as the piston is actuated. The hydraulic cylinder contains a column of oil in the cylinder between the piston and a supply line connected to the cylinder and coming from a water main such as a city domestic supply. An exhaust line off the supply line exhausts on the piston downstroke to a drain or sump. Each of the supply line and the exhaust line is controlled by a solenoid operating valve electrically connected to a manual switch. Preferably a limit switch located to be actuated at the bottom of the downward travel of the speaker's apparatus closes the exhaust valve before the oil-water interface in the cylinder reaches the cylinder outlet to the supply line. The supply entry of the cylinder may be baffled to reduce water turbulence to preserve the interface between water and oil in the cylinder.

Abstract: A logging truck having a load supporting frame provided with a plurality of log-supporting bunks has a false bunk arrangement disposed over the load supporting center of a wheel assembly supporting the load supporting frame for applying a positive force to logs disposed on the bunks and relieving flexing of the load supporting frame.

Abstract: A novel mechanical power unit for use in stool and the like construction having features allowing its easy application to great variety of additional uses. The power unit has a ram which is displaced within a cylinder under the influence of hydraulic fluid driven by compressed air. The fluid and compressed air are carried in a reservoir generally surrounding the cylinder, formed by the outer wall of the cylinder and the inner wall of a generally concentric shell welded permanently at its ends to the cylinder. A manually operable, normally closed valve is provided in the base of the cylinder to control transfer of fluid between the interior of the cylinder and the reservoir to operate the power unit, causing the ram to extend or retract with respect to the cylinder, and holding the ram in any amount of extension when the valve is closed.