Hand crank for a landing gear

A hand crank for a landing gear is described, the hand crank having a main body provided at a first end with a connecting element for fastening the hand crank to an input shaft of the landing gear and formed at an opposite, second end to rotate the hand crank. The hand crank only allows torque to be transmitted from the hand crank to the input shaft if the operator holds the hand crank with at least one hand. A clutch is arranged in the force flow between the first end of the main body and the connecting element, wherein the clutch is held in an open disconnected position and is moved into a force-locked connection position by operating an actuating element arranged at the second end.

FIELD OF THE INVENTION

The invention relates to a hand crank for a landing gear including a main body provided at a first end with a connecting element for fastening the hand crank to an input shaft of the landing gear and formed at an opposite, second end to rotate the hand crank. In addition, the invention is also implemented on a landing gear.

BACKGROUND OF THE INVENTION

Landing jacks are often mounted in pairs on semitrailers and keep them at a constant height after separation from a towing vehicle. For this purpose, the landing jacks can be telescoped and are usually adjusted with a hand crank between a retracted and an extended position. The operator stands on the side of the semi-trailer and turns the hand crank clockwise or counter-clockwise to raise or lower the semi-trailer. For safety reasons, the operator should stand securely and operate the crank handle with both hands on a crank sleeve without letting go until the intended extension state of the landing gear(s) is reached.

Document DE 76 05 307 U discloses a corresponding hand crank with a main body having at the first end a connecting element in the form of a fork piece, which is permanently fastened to the input shaft of a landing gear by means of a bolt. When not in use, the hand crank can be tilted away with respect to the input shaft and hung in a crank holder. The crank can be locked in a position of use by actuating a spring-loaded lug and moving the crank with respect to the drive shaft. Occasionally, however, contrary to the safety instructions, in particular when lowering the trailer, the operator sometimes sets the hand crank in a rapid rotary movement with one hand and releases the hand crank, so that the hand crank performs a few rotations due to the angular momentum.

This practice allows the trailer to lower uncontrollably during the phase in which the hand crank is not held by the operator. There is also a risk for the operator to be hit and injured by the rapidly rotating hand crank.

SUMMARY OF THE INVENTION

The object of the invention was therefore to provide a hand crank which only allows torque to be transmitted from the hand crank to the input shaft if the operator holds the hand crank with at least one hand.

The underlying object of the invention is solved with a hand crank for a landing gear, the hand crank comprising: a main body provided at a first end with a connecting element for fastening the hand crank to an input shaft of the landing gear and formed at an opposite, second end to rotate the hand crank, wherein a clutch is arranged in the force flow between the first end of the main body and the connecting element, wherein the clutch is held in an open disconnected position and is moved into a force-locked connection position by operating an actuating element arranged at the second end. The hand crank can be fastened to the input shaft of a landing gear with the connecting element. The connecting element ensures a permanent, mechanical connection of the crank handle and the input shaft with respect to the input shaft.

At the second end of the main body there is preferably arranged a crank sleeve rotatably mounted in its circumferential direction, on which the operator grips the hand crank and sets it in rotation. As an alternative to a crank sleeve, the second end can also be formed with a smooth surface which slides over the palm of the operator's hand with little friction when the hand crank is actuated.

Typically, the first and second ends of the main body are aligned axially parallel to one another. A central part of the main body arranged between the first and second ends runs essentially perpendicular to the first and second ends of the main body. The connecting means engages on the first end of the main body and, depending on the switching position of a clutch arranged on the first end, is connected to the first end either in a rotationally fixed or rotatable manner. When the hand crank is actuated, the second end rotates around the first end at a distance from the central part.

The clutch is connected via a force transmission means to the actuating element arranged at the second end of the main body, so that an operator can only extend the landing gear if he simultaneously operates the actuating element during a rotary movement of the hand crank, preferably by means of the crank sleeve. When actuated, the actuating element initiates a closing of the clutch in a force-locked connection position. The force-locked connection position can be realized by a positive connection or a frictional connection of the clutch. This initially has the advantage that the input shaft rotates and thus the landing gear(s) does/do not move unless the hand crank remains in the operator's hand during operation. The operation using the angular momentum without holding the hand crank could still take place, but does not lead to a movement of the landing gear(s) since no torque is transmitted to its input shaft due to the clutch then being opened. As a result, the operator refrains from accelerating the crank handle at all with an angular momentum and then releasing it, so that the risk of being hit by a crank handle that is uncontrollably wobbling around the input shaft is also reduced.

The clutch and the actuating element are preferably connected to one another via a force transmission means. The force transmission means can be a tensile force element, in particular a rope, a Bowden cable or a chain, or a compressive force element, in particular a pressure cable, a pressure chain or a hydraulic transmitter. A Bowden cable is understood to mean a movable machine element for transmitting a mechanical movement as well as compressive and tensile forces by means of a flexible combination of a wire rope and a sheath that is pressure-resistant in its axial direction.

The clutch advantageously has a release rod to which the force transmission means is fastened. With the help of the power transmission means, the release rod can be moved with respect to the first end, in particular in its axial direction. Depending on whether the release rod comes into a rotationally fixed or a rotatable connection position with the first end by a movement in the axial direction, the clutch is in an open disconnected position or a force-locked connection position.

According to a particularly favorable embodiment, the release rod engages in a rotationally fixed manner on the connecting element and is designed with a torque receiving section. The torque receiving section can have a polygonal or oval profile in cross section, which allows form-fitted torque transmission with the main body. Alternatively, an elastic or roughened element for a frictional torque transmission can also be present.

It has proven to be particularly useful if the clutch has a torque transmission section which is arranged in a stationary manner at the first end of the main body. The torque transmission section is formed complementary to the torque receiving section, so that when the clutch is actuated by means of the actuating element and the force transmission means, the torque receiving section and the torque transmission section interlock. The torque receiving section is preferably formed on the inside of the main body or is formed from a section-wise deformation of the main body in the region of the first end.

The release rod is expediently guided so as to be displaceable in the axial direction with respect to the main body, and when the actuating element is actuated, the torque receiving section engages with the torque transmission section.

In an open disconnected position of the clutch, the torque receiving section is arranged contactlessly with the first end of the main body. When the actuating element is actuated, the torque receiving section moves in the axial direction and comes into engagement with the torque transmission section, so that the clutch is in a force-locked connection position. In the force-locked connection position of the clutch, the torque receiving section is surrounded concentrically by the torque transmission section, in particular in the radial direction.

The torque transmission section can have a cross section which is shaped complementary to the torque receiving section. As a result, the torque receiving section can be received by the torque transmission section in a force-locked connection position of the clutch.

The clutch can, for example, be held in an open disconnected position by a spring element.

The main body is preferably a tube and the clutch and/or the spring element is/are arranged inside that tube. This leads to the advantage that, in particular in the region of the first end, no components protrude from the main body. The force transmission means can also extend through the inside of the main body in the axial direction from the first end to the second end. A tube is understood to be an elongated hollow body having a length which is generally much greater than its diameter. The tube is made of a material that is rigid under the expected operational loads and can have a circular cross section, which is the optimal design for the most common applications. An increased stiffness can also be achieved with rectangular, oval and other cross sections. The main body is regularly designed as an integral tubular body.

According to a first advantageous embodiment, the spring element is a compression spring element or tension spring element arranged at the first end. With a compression spring element, the restoring force of the spring element is a compression force and with a tension spring element it is a tension force.

The compression spring element or the tension spring element is advantageously held stationary with respect to the release rod with an end section and stationary with respect to the first end of the main body.

According to a second, alternative embodiment, the spring element can be a tension spring element arranged at the second end of the main body.

The tension spring element is expediently fixed with one end section to the actuating element and with an opposite end section to the second end of the main body.

The actuating element is expediently slidably mounted with respect to the second end of the main body, in particular in the axial elongation of the second end. As a result, the actuating element can be operated simultaneously while the crank sleeve is rotating and rotates around the second end of the main body, so that the operator does not have to grip around on the hand crank and the hand crank does not slip over the actuating element while rotating.

A particularly advantageous embodiment can be achieved if the actuating element has an attachment point for the force transmission means. An actuation of the actuating element thus leads directly to an adjustment of the attachment point of the force transmission means and thus to a change in the switching position of the clutch. In the opened disconnected position of the clutch the attachment point is preferably in a close position next to the second end of the main body.

In the force-locked connection position of the clutch, the attachment point is located in a spaced position with respect to the second end of the main body.

The attachment point advantageously comprises an adjusting device for adjusting the length of the force transmission means. The adjusting device is used in particular to adjust the length of the force transmission means and thereby the point of a force-locked connection position of the clutch. This is useful, for example, in order to compensate for tolerances of the individual components and to compensate for wear-related changes in length of the power transmission means.

An embodiment is particularly preferred in which the actuating element is an actuating sleeve which at least partially overlaps the second end of the main body in the axial direction. In the overlapping area, the actuating sleeve is held radially by the second end. The actuating sleeve can be slidably guided in the axial direction with respect to the second end for switching the clutch into a force-locked connection position.

The actuating sleeve should at least partially project from the crank sleeve. In this embodiment, the actuating sleeve is arranged in the radial direction between the second end and the crank sleeve.

The actuating sleeve is advantageously mounted so as to be rotatable with respect to the crank sleeve and the second end of the main body. The actuating sleeve is thereby decoupled from the rotary movement of the crank sleeve and rotates freely with respect to the second end of the main body. This has the advantage that the actuating sleeve can be comfortably held by a second hand of the operator without turning in the palm of the hand.

According to a further embodiment, a lever can be pivotally mounted on the actuating element or on the crank sleeve, wherein the load arm is supported by the second end of the main body. The lever simplifies an axial adjustment of the actuating element in the axial direction of the second end of the main body.

The spring element expediently engages the actuating element or the crank sleeve and the lever. As a result, the lever is pulled into a position protruding with respect to the actuating element or the crank sleeve and can be gripped by an operator. The crank sleeve is expediently mounted on the second end of the main body in such a way that axial forces can be transmitted. This is particularly necessary if the operator actuates the lever and the actuating element has moved into a position disengaged with respect to the second end due to the action of the lever.

An axial drive path of the actuating element can preferably correspond to an axial drive path of the release rod and/or an axial drive path of the connecting element.

The invention also relates to a landing gear with an input shaft and a hand crank described above, the landing gear having an outer sleeve and an inner sleeve telescopically guided therein with a support foot formed on the end side thereof and the inner sleeve being movable relative to the outer sleeve by actuating the hand crank in the force-locked connection position of the clutch.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a perspective view on a pair of landing gears50each having an outer sleeve53with a square profile and an inner sleeve54slidably guided therein with the same profile shape. In their upper section, the outer sleeves53each have a mounting plate56, with which the landing gears50are fastened to a vehicle, in particular to a semitrailer (not shown).

In order to set the extended state of the inner sleeve54with respect to the associated outer sleeve53which is fixedly attached to the vehicle, an input shaft51protrudes from the landing gear50located in front of the image plane being connected in a rotationally fixed manner to a hand crank1. The input shaft51is kinematically coupled to a connecting shaft52running between the two landing gears50, so that the inner sleeves54of both support jacks50are retracted or extended simultaneously by rotating the hand crank1clockwise or counterclockwise. Each inner sleeve54is extended until support feet55arranged at the free ends of the inner sleeves54stand on the ground and hold the load of the vehicle acting in the direction of normal force.

After coupling of the trailer, the inner sleeves54are retracted until they are almost completely received by their associated outer sleeve53as shown inFIG. 1.

The hand crank1has a main body10with an essentially Z-shape. A first end20of the main body10faces the input shaft51and carries a connecting element21designed as a fork piece, which projects over the input shaft51on two opposite sides and passes through the input shaft51by means of a connecting bolt21b.

A second end30of the main body10is aligned axially parallel to the first end20and carries a crank sleeve31which is rotatably mounted thereon. The crank sleeve31is taken by the hand of the operator for moving the extension state of the landing gears50by rotating the hand crank1about the input shaft51. Between the first end20and the second end30runs a middle part13of the main body10, the axial extent of which extends essentially perpendicular to the axial extent of the first and second ends20,30.

At the second end30, an actuating element32is also arranged directly adjacent to the crank sleeve31, with which a clutch22located at the first end20can be operated. The actuating element32is mounted in particular in the axial extension of the crank sleeve31and can be gripped by the hand of the operator for actuation. The actuating element32is connected to the clutch22arranged at the first end20by means of a force transmission means11. The force transmission means11runs over its entire axial length within the main body10and is indicated inFIG. 1as a dotted line.

FIG. 2shows a cross section of the first end20of the main body10with the clutch22installed therein. The main body10is designed as a tube with an interior12which receives the clutch22in such a way that no components protrude from the main body10in the radial direction.

The clutch22comprises, as necessary components, a release rod23with a one-piece, integrally formed torque receiving section24interacting with the torque transmission section25in the force-locking connection position.

The release rod23engages in a rotationally fixed manner on the connecting element21and extends coaxially into the interior12of the first end20. In the interior12, the release rod23is formed in sections with a support piston27, which projects radially in the direction of the inner wall of the first end20of the main body10relative to the release rod23. The support piston27has an outer diameter which corresponds approximately to the inner diameter of the interior12and thereby gives the release rod23lateral guidance during movement in the axial direction x.

The force transmission means11engages the end section of the release rod23inserted into the first end20and moves the release rod23in its axial direction x depending on the position of the actuating element32. The force transmission means11preferably comprises a Bowden cable, the wire rope11aof which engages the release rod23and is guided through an opening15arranged in an inner retaining wall14aof the main body10. The pressure-resistant case11bof the Bowden cable is supported on the inner retaining wall14aaround the opening15.

The torque receiving section24of the release rod23is oriented in accordance withFIG. 2in the open disconnected position of the clutch22in an axially offset manner with respect to a torque transmission region25which is complementary shaped at the first end20.

The torque receiving section24and the torque transmission section25can in particular be formed from a polygonal, star-shaped or oval profile, which forms a positive connection as soon as the torque receiving section24and the torque transmission section25are displaced in the axial direction x and come into active engagement.

In the opened disconnected position of the clutch22, the torque receiving section24is located in the image plane to the right of the torque transmission section25, is moved to the left by a tensile force applied by the force transmission means11to the release rod23to reach a force-locked connection position, and thereby moves into the torque transmission section25as can be seen particularly well inFIG. 3.

The torque transmission section25is designed to be stationary at the first end20of the main body10, in particular by compression molding.

Without a tensile force being transmitted from the actuating element32to the force transmission means11, a spring element40, which in the embodiment ofFIGS. 2 and 3is designed as a compression spring element41, presses the release rod23to the right in the image plane, so that the clutch22is in an open disconnected position and no torque is transmitted to the connecting element21when the hand crank1rotates.

The spring element40is supported with its end section43on a stationary section of the release rod23; in the exemplary embodiment shown on an end face of the support piston27, With its opposite end section44, the spring element40contacts a fixed portion of the first end20of the main body10; in the shown embodiment on an end face of a smaller-diameter cross section26of the torque transmission section25within the interior12.

The spring element40of the embodiment according toFIG. 2andFIG. 3is inserted into an annular space between the release rod23and the inner wall of the first end20and surrounds the release rod23coaxial. The spring element40is designed in terms of its axial length and its spring constant such that the torque receiving section24is pressed out of the torque transmission section25in the axial direction by the spring element40without the external force of the actuating element32.

FIG. 3shows the force-locked connection position of the clutch22, in which the torque receiving section24of the release rod23is drawn into the free cross section26of the torque transmission section25by the force transmission means11against the spring force of the spring element40. The release rod23has moved into the first end20of the main body10according to drive path xAand has taken the connecting element21, which is formed thereon, by the same amount according to drive path xV. The force-locked connection position of the clutch22is maintained as long as the operator actuates the actuating element32arranged at the second end30of the main body10and applies a tensile force to the release rod23via the force transmission means11which is greater than the spring force of the spring element40.

If, contrary to the safety instruction, the operator releases the crank handle1and thus also the actuating element32during actuation, the spring element40pulls the release rod23and with it the torque receiving section24out of the torque transmission section25and automatically brings the clutch22into an open disconnected position which no longer transmits torque to the input shaft51of the landing gear50.

An alternative embodiment is shown inFIG. 4, in which the spring element40is also designed as a compression spring element41and is arranged in a section of the first end20, seen from the connecting element21, beyond the torque transmission section25. The spring element40is supported here with its end section43on a support ring28which is designed to be stationary on the release rod23and with its opposite end section44on the inner retaining wall14awhich is arranged in the first end20of the main body10.

FIG. 5shows a further exemplary embodiment with a spring element40in the form of a tension spring element42. The tension spring element42is stretched by actuating the force transmission means11and, when the tensile force continues, allows the torque receiving section24of the release rod23to be displaced into the torque transmission section25. Without a tensile force applied by the force transmission means11, the release rod23together with the torque receiving section24is moved in the axial direction x of the connecting element21due to the restoring force of the tension spring element42and released from the active engagement with the torque transmission section25.

The tension spring element42is arranged between an outer retaining wall14bformed on the free end of the first end20and the end face of the support piston27and is fixed to the support piston27and to the outer retaining wall14bby means of a tension spring fastener45respectively. The tension spring element42is located in an annular space between the inner wall of the first end20and the release rod23and preferably surrounds the release rod23coaxially.

FIG. 6shows an enlarged cross section of the second end30of the main body10, on which the crank sleeve31is rotatably mounted. A displacement of the crank sleeve31relative to the second end30is prevented in the axial direction x by means of a thrust bearing36.

The main body10passes through the crank sleeve31completely and also carries, preferably also rotatably mounted, the actuating element32.FIG. 6shows the actuating element32arranged at the second end30when the clutch22arranged at the first end20is in the disconnected position.

The actuating element32is designed as an actuating sleeve and projects axially into the crank sleeve31, which has an enlarged inner diameter31afor this purpose. The actuating element32is immersed at most in the enlarged inner diameter31a. In the region of the enlarged inner diameter31a, the crank sleeve31overlaps the actuating sleeve32in the radial direction. This overlapping section is chosen to be larger in the axial direction x than a drive path xSof the actuating element32, which in turn corresponds to the drive path xAof the release rod23and the drive path xVof the connecting element21at the first end20. This ensures that the actuating element32, regardless of its position variable in the axial direction x, is always overlapped by the actuating sleeve32, which is held stationary in the axial direction x, and is guided in the radial direction.

The force transmission means11is fastened to the actuating element32in a attachment point33, the attachment point33being in a near position X1close to the second end30. The attachment point33can be adjustable in the axial direction x by means of an adjusting device34, so that a preload of the force transmission means11can be set. The preload of the force transmission means11should be selected such that the unactuated actuating element32is pulled against the enlarged inner diameter31aof the crank sleeve31without clearance. Because of its thrust bearing36, the crank sleeve31forms an abutment for the actuating element32.

InFIG. 7, the actuating element32is moved to the left in the image plane by the drive path xSand held there, so that the attachment point33of the force transmission means11is in a spaced position X2from the second end30. The actuating element32has thereby brought the torque receiving section24located at the first end20into active engagement with the torque transmission section25.

FIG. 8shows a further embodiment in which the spring element40is arranged in the region of the second end30of the main body10. In this embodiment, if a shear-resistant force transmission means11is used, a spring element40in the region of the first end20is not necessary.

The spring element40according toFIG. 8is used as a tension spring element42and is fixed with its end section43to the second end30of the main body10, preferably to an outer retaining wall14b, and with its opposite end section44to the actuating element32by means of a tension spring fastener45and passes concentrically through the actuating element32. The tension spring element42has pulled the actuating element32as far as possible towards the second end30, so that the attachment point33of the force transmission means11has reached a close position X1with respect to the second end30of the main body10.

The side of the actuating element32facing the second end30completely fills out the enlarged inner diameter31aand is supported in this area in the axial direction x on the crank sleeve31. The tension spring element42is received over its entire extent by the actuating element32designed as an actuating sleeve.

In the above-described embodiments relating to the second end30according toFIGS. 6 to 8, the actuating element32is formed on its side facing away from the second end30with a collar38preferably closed in the circumferential direction which prevents slipping off the hand of the operator in an axial direction x.

An even more convenient operation can be achieved by means of a lever35pivotably mounted on the actuating element32according to the embodiment shown inFIG. 9andFIG. 10. The pivotable lever35has a load arm35a, which, regardless of its position, always extends into the interior of the actuating element32designed as an actuating sleeve and is there opposed to the second end30of the main body10, in particular to an outer retaining wall14brunning perpendicular to the axial direction x.

FIG. 9shows an open disconnected position of the clutch22arranged at the first end20with an actuating element32positioned as close as possible to the second end30. The actuating element32is also completely immersed in the enlarged inner diameter31aof the crank sleeve32. A force applied arm35bof the lever35projects with respect to the actuating element32in its radial direction and can be gripped particularly well by an operator in this position. A spring element40designed as a tension spring element42engages with its end section43by means of a tension spring fastener45on the actuating element32and with its opposite end section44by means of a tension spring fastener45on the force applied arm35bof the lever35.

By pivoting movement of the force applied arm35bin a direction facing away from the crank sleeve31, the load arm35apresses against the second end30and, as shown inFIG. 10, pushes the entire actuating element32away from the second end30. After reaching the spaced position X2of the attachment point33with respect to second end30, the clutch22is switched into a force-locked connection position at the first end20due to the force transmitted by the operator from the force transmission means11.

However, the tension spring element42is only tensioned for the duration of a force applied by the operator.

As soon as the operator releases the crank handle1and thus also the actuating element32, the tension spring element42pulls the lever35back into the starting position according toFIG. 9. Because the load arm35ais connected to the second end30by load arm connection means37transmitting tensile forces, the actuating element32also moves back along axial direction x until a stop of the actuating element32within the enlarged inner diameter31ais reached. In this position, the clutch22located at the first end20of the main body10is closed.

LIST OF REFERENCE NUMBERS