Abstract: A positioning structure of a clamper of a threading machine for a racket contains: a rack, an engagement protrusion, an operation member, and two springs. A fixing holder is erected on a support plate of the threading machine, and the rack includes multiple first teeth, the fixing holder includes an accommodation chamber with an opening. The engagement protrusion is received in the accommodation chamber and includes a toothed extension on which multiple second teeth are formed. The engagement protrusion further includes a recess and an abutting fence. The operation member includes a drive portion and a push portion. The two springs are mounted on a top of the engagement protrusion, and two ends of each spring abut against the engagement protrusion and the fixing holder respectively so that each spring forces the engagement protrusion to engage with the rack.

Abstract: A down-pressed clamp base includes: a main body having a space and a passage in communication with the space via a connection perforation; a transmission member fitted in the connection perforation; a leverage mechanism including a lever and a link, the link being pivotally connected with the lever and positioned in the passage, a free end of the link being directed to the transmission member; a fastening mechanism disposed in the space; and a string holding mechanism disposed on the main body for holding a racket string. When pressing down the leverage mechanism, the clamp base is fixed on the racket stringer in an operation mode meeting ergonomics. When the leverage mechanism is pressed down, the action forces of the lever, the link and the transmission member fall on the same straight line, whereby the clamp base is fixed on the racket stringer by a fixed fastening force.

Abstract: A positioning device for holding member of a sport racket stringing machine includes a rack which is engaged with the top board of the stringing machine and has multiple one-way ratchet teeth. The holding member has a chamber and a contact member is movably located in the chamber and inclinedly engaged with the ratchet teeth of the rack to position the holding member. A spring is connected between the body and the contact member to urge the contact member to contact the rack. The operation member is pivotably connected to the chamber. The operation member has a driving portion and a positioning portion with a curved operation portion connected therebetween. The operation portion is pivotably connected to the body. The top end of the contact member extends between the driving portion and the positioning portion and the driving portion pivots the contact member to move the holding member.

Abstract: A clamping assembly for stringing machine includes a slide member, a positioning device, a control device and a rail. The positioning device and a tube are located on two ends of the slide member. The control device includes a pin, a ring-shaped member and a knob. The pin is pivotably connected with the knob. The tube includes an engaging section and a receiving section. The receiving section has a positioning pin and a spring which biases the positioning pin so as to move the positioning pin axially. The knob having a pin hole defined in an underside thereof and can be securely positioned by inserting the insertion member into the pin hole. The knob includes a release button which is connected with a bolt. When pressing the release button, the bolt moves the insertion member which releases the knob.

Abstract: An ergonomically-designed racquet stringing machine. The stringing machine includes an electronic control unit coupled to a platform and/or to a height adjustment assembly. The control unit is capable of generating a control signal to automatically adjust at least one parameter of the machine, such as machine height, angle of stringing platform, or string tension, based upon a selected user profile. A method of controlling tension in a racquet while stringing the racquet entails the use of the stringing machine.

Abstract: A work table tilting apparatus for a stringing machine for tennis rackets which allows free tilt at any angle toward the front of the user.

Abstract: A clamping device for stringing machine includes a slide member, a positioning device, a control device and a rail. The positioning device and a tube are located on two ends of the slide member. An extension of a clamping device is inserted into the tube. The control device includes a pin, a ring-shaped member and a knob. The pin is pivotably connected with the knob. A torsion spring is received in an annular space of the knob so as to rotate the knob to its original position. The tube includes an engaging section and a receiving section. The receiving section has a positioning pin and a spring which biases the positioning pin so as to move the positioning pin axially. The knob having a pin hole defined in an underside thereof and can be securely positioned by inserting the insertion member into the pin hole.

Abstract: A racket stringer includes a work table, and two opposite fixing devices each mounted on the work table and each including a rack, a guide plate, two foot posts, a support shaft, and a press rod. Thus, the fixing device has a quick positioning microadjustment function. In addition, the fixing device can be displaced easily and rapidly, thereby facilitating the user operating the racket sag stringer.

Abstract: A string drawing electrical device for a racquet has a casing, a string holder, an actuating device and a control unit. The string holder is rotatably attached to a panel of the casing. The actuating device is mounted in the casing and provides two functions, feeding and reversing, to the string holder. The control unit is mounted in the casing for controlling the actuating device to act. Accordingly, the string drawing electrical device can tighten and loosen the string, and the tensile force of the string of the racquet can be accurately controlled.

Abstract: A universal stringing machine has a pair of risers, having oppositely facing, V-shape bearing members for engaging opposed inside surfaces of a racquet frame. Preferably, each riser has a pair, and most preferably three, laterally spaced bearing members, in which each member can pivot between a first, e.g., up, position, for engaging the racquet, and a second, e.g., down, position, in which such member will be out of the way. Also, the two outside V-shaped bearing members are laterally adjustable toward and away from one another. In this manner, either the center bearing member, or the outside members, can be chosen to mount the racquet, depending upon racquet type, and also the distance between the outside bearing members can be adjusted so that the bearing members do not interfere with the strings. Preferably, the V-shaped engagement surface of the bearing members is covered with a plastic or elastomeric sleeve or cover, and can swivel about an axis perpendicular to the strings.

Abstract: A method of improving ground soil irrigation by employing an additive or amendment in the form of an improved synthetic solution grade calcium sulfate dihydrate composition. This composition is formulated by contacting a calcium compound having a calcium cation with a chemical agent enabling the calcium compound to yield calcium ions upon reaction with the chemical agent and which enables the calcium cation to react with an anion of the chemical agent forming a second calcium compound. The second calcium compound is reacted with a sulfur containing acid, such as sulfuric acid, to thereby form a calcium sulfate dihydrate. The compound has improved suspension characteristics and will remain in suspension for a much longer period of time than a conventional solution grade calcium sulfate dihydrate.