FRAMELESS LIGHTWEIGHT POST-TENSIONING JACK AND METHOD FOR USING SAME

Abstract

A frameless lightweight jack may include a pressure cylinder, the pressure cylinder having a pressure cylinder passage and a pressure cylinder body including a body passage, the pressure cylinder body mechanically coupled to the pressure cylinder. A first and a second hydraulic actuator may be coupled to the pressure cylinder body on a proximal end, the actuators are in hydraulic communication through a cylinder loop hose connected to each hydraulic actuator. An extending body may be coupled to the hydraulic actuators, and may include an extending body passage, wherein the pressure cylinder passage, the pressure cylinder body passage, and the extending body passage are aligned to form a tension member channel. A strand grabber assembly may be mechanically coupled to the extending body, wherein the pressure cylinder, pressure cylinder body, and extending body are comprised of aluminum, titanium, fiber reinforced plastic, polymers, or carbon fiber.

Description

FIELD OF THE DISCLOSURE

The present disclosure relates to post-tensioning jacks and methods of use.

BACKGROUND INFORMATION

Pre-stressed concrete is structural concrete in which internal stresses are introduced to reduce potential tensile stresses in the concrete resulting from applied loads. Pre-stressing may be accomplished by post-tensioned pre-stressing or pre-tensioned prestressing. In post-tensioned pre-stressing, a tension member is tensioned after the concrete has attained a desired strength by use of a post-tensioning tendon. The post-tensioning tendon may include for example and without limitation, anchor assemblies, the tension member, and sheathes.

Traditionally, a tension member is constructed of a material that can be elongated and may be a single or a multi-strand cable. The tension member may be formed from a metal, such as reinforced steel. The post-tensioning tendon traditionally includes an anchor assembly at each end. The tension member is fixedly coupled to a fixed anchor assembly positioned at one end of the post-tensioning tendon, the “fixed end,” and stressed at the stressed anchor assembly positioned at the opposite end of the post-tensioning tendon, the “stressing end” of the post-tensioning tendon.

GTI's post-tensioning jacks are durable, field tested and proven designs with an ergonomic handle to reduce operator fatigue. The single acting PTJ models with spring seating or power seating have proven ideal for slab-on-grade and other applications. Double acting DA models may have an 8.5″ stroke and may be machined from steel billets. They may feature standard power seating and have gun-drilled hydraulic fluid passages. Nose lengths may vary and a full line of gripper sizes are usually available to stress most common strand sizes.

While GTI's jacks are industry leading and successfully used throughout the industry, they can be heavy, which may make use awkward in certain situations. Moreover, existing jacks present a pinch hazard when they return from a working position to a resting position.

Thus, it may be beneficial to provide a lightweight post-tensioning jack that also maintains a gap in a resting position to avoid potential pinch hazards.

SUMMARY OF EXEMPLARY EMBODIMENTS

The following is intended to be a brief summary of the exemplary embodiments of the present disclosure, and is not intended to limit the scope of the exemplary embodiments.

In some aspects, the techniques described herein relate to a frameless lightweight jack including: a pressure cylinder, the pressure cylinder having a pressure cylinder passage; a pressure cylinder body, the pressure cylinder body being a block through which a pressure cylinder body passage is formed, the pressure cylinder body mechanically coupled to the pressure cylinder; a first and a second hydraulic actuator, the first and the second hydraulic actuator each coupled to the pressure cylinder body on a proximal end, wherein the first and the second hydraulic actuator are in hydraulic communication through a cylinder loop hose connected to a port in a distal end of each of the first and second hydraulic actuator; an extending body, the extending body coupled to the first and the second hydraulic actuator, the extending body being a block through which an extending body passage is formed, wherein the pressure cylinder passage, the pressure cylinder body passage, and the extending body passage are aligned to form a tension member channel; and a strand grabber assembly, the strand grabber assembly mechanically coupled to the extending body; wherein the pressure cylinder, pressure cylinder body, and extending body are included of aluminum, titanium, fiber reinforced plastic, polymers, or carbon fiber.

In some aspects, the techniques described herein relate to a frameless lightweight jack, wherein the hydraulic actuators are pneumatically actuated.

In some aspects, the techniques described herein relate to a frameless lightweight jack, wherein the first and the second hydraulic actuator each have an internal piston.

In some aspects, the techniques described herein relate to a frameless lightweight jack, wherein the first and the second hydraulic actuator are each coupled to the pressure cylinder body at a proximal end of the internal piston of each hydraulic actuator

In some aspects, the techniques described herein relate to a frameless lightweight jack, wherein the strand grabber assembly includes: a strand grabber handle; a strand grabber; a grabber block; and a grabber retaining plate.

In some aspects, the techniques described herein relate to a frameless lightweight jack, wherein the first and the second hydraulic actuator are free floating on the distal ends.

In some aspects, the techniques described herein relate to a frameless lightweight jack, wherein the port in the distal end of each of the first and second hydraulic actuator is on a circumferential surface of each hydraulic actuator.

In some aspects, the techniques described herein relate to a frameless lightweight jack including: a pressure cylinder body, the pressure cylinder body being a block through which a pressure cylinder body passage is formed; a first and a second hydraulic actuator, the first and the second hydraulic actuator each coupled to the pressure cylinder body on a proximal end, wherein the first and the second hydraulic actuator are in hydraulic communication through a cylinder loop hose connected to a port in a distal end of each of the first and second hydraulic actuator; an extending body, the extending body coupled to the first and the second hydraulic actuator, the extending body being a block through which an extending body passage is formed, wherein the pressure cylinder body passage and the extending body passage are aligned to form a tension member channel; and a strand grabber assembly, the strand grabber assembly mechanically coupled to the extending body; wherein the pressure cylinder body is configured to not touch the extending body when the frameless lightweight jack is in a retracted position.

In some aspects, the techniques described herein relate to a frameless lightweight jack, wherein there is a gap between the pressure cylinder body and the extending body when the frameless lightweight jack is in the retracted position.

In some aspects, the techniques described herein relate to a frameless lightweight jack, wherein the gap is at least 1 inch.

In some aspects, the techniques described herein relate to a method of using a frameless lightweight jack including: positioning the frameless lightweight jack in a retracted position so as to abut a concrete structure with a tensioning member, the lightweight jack including: a pressure cylinder body, the pressure cylinder body being a block through which a pressure cylinder body passage is formed; a first and a second hydraulic actuator, the first and the second hydraulic actuator each coupled to the pressure cylinder body on a proximal end, wherein the first and the second hydraulic actuator are in hydraulic communication through a cylinder loop hose connected to a port in a distal end of each of the first and second hydraulic actuator; an extending body, the extending body coupled to the first and the second hydraulic actuator, the extending body being a block through which an extending body passage is formed, wherein the pressure cylinder body passage and the extending body passage are aligned to form a tension member channel; and a strand grabber assembly, the strand grabber assembly mechanically coupled to the extending body; wherein the pressure cylinder body is configured to not touch the extending body when the frameless lightweight jack is in a retracted position; engaging the tensioning member with the strand grabber assembly; moving the frameless lightweight jack from a retracted position to an extended position so as to tension the tension member; moving the frameless lightweight jack from the extended position to the retracted position, such movement resulting in a gap between the pressure cylinder body and the extending body.

These and other objects, features and advantages of the exemplary embodiments of the present disclosure will become apparent upon reading the following detailed description of the exemplary embodiments of the present disclosure, when taken in conjunction with the accompanying paragraphs.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present disclosure, together with further objects and advantages, may best be understood by reference to the following description taken in conjunction with the accompanying drawings.

FIG. 1 depicts views of a lightweight post-tensioning jack consistent with certain embodiments of the present disclosure.

FIG. 2 is an exemplary exploded view of a lightweight post-tensioning jack consistent with certain embodiments of the present disclosure.

FIG. 3 depicts a front view of a lightweight post-tensioning jack consistent with certain embodiments of the present disclosure.

FIG. 4 depicts a top view of a lightweight post-tensioning jack consistent with certain embodiments of the present disclosure.

FIG. 5 depicts a side view of a lightweight post-tensioning jack consistent with certain embodiments of the present disclosure.

These and other objects, features and advantages of the exemplary embodiments of the present disclosure will become apparent upon reading the following detailed description of the exemplary embodiments of the present disclosure, when taken in conjunction with the appended claims.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Certain embodiments of the present disclosure are directed to a frameless lightweight jack for stressing a tension member. The frameless lightweight jack may be hydraulically powered, such as through hydraulic fluid delivered by a hydraulic pump having a hydraulic fluid source. A pressure gauge may be included to measure when a tendon has been sufficiently tensioned. In other exemplary embodiments, the frameless lightweight jack may be battery powered, thereby eliminating the need for hydraulic lines and a pump system. In exemplary embodiments of the present disclosure, the frameless lightweight jack may provide over 9000 psi of tension on a tendon as compared with around 5000 psi on conventional designs. In some embodiments, the frameless lightweight jack may include a digital display that provides a real-time pressure reading as a tendon is tensioned FIG. 1 depicts frameless lightweight jack 100 in a (fully) retracted or resting position. In certain embodiments, frameless lightweight jack 100 may have a retracted/resting position and an extended/working position. A hydraulic pump may be fluidly connected to lightweight jack 100 through one or more hydraulic hoses. Lightweight jack 100 may have a single hydraulic fluid connection point at servicing tee 112. In certain embodiments, light weight jack 100 may include pressure cylinder 120. Pressure cylinder 120 may be frustoconical. In some embodiments, pressure cylinder 120 may be hollow and with a section removed for installing and removing a tensioning tendon, forming cylinder aperture 121. When in use, pressure cylinder 120 may interface with an anchor that houses a tendon wedge. In some embodiments, pressure cylinder 120 may include a tongue on the surface that interfaces with the anchor. In these embodiments, the anchor has a groove designed to receive the tongue of pressure cylinder 120. The tongue and groove design may result in easy alignment of lightweight jack 100 with the anchor, and therefore also the tensioning tendon.

Wedge setter 122 may be positioned within pressure cylinder 120 and secured by pressure cylinder 120 and pressure cylinder body 130. In some embodiments, wedge setter 122 may be conical with a section removed, forming wedge setter aperture 123, again for ease of installing and removing a tensioning tendon into frameless lightweight jack 100. Wedge setter 122 may be hollow for receiving a tensioning tendon. Pressure cylinder 120 and wedge setter 122 may be adapted to receive a portion of a tension member through pressure cylinder passage 133.

Pressure cylinder 120 may be mechanically coupled to pressure cylinder body 130 such that pressure cylinder passage 133 and cylinder body passage 132 align. “Mechanically coupled” for purposes of this disclosure, may include, but not be limited to, threaded couplings, press fitting, mechanical welding, chemical welding, friction welding, thermal coupling or welding, electrical welding, optical welding, beam-energy welding, etc. Pressure cylinder body 130 may be of any shape and may be a block through which cylinder body passage 132 traverses. When frameless lightweight jack 100 is in the (fully) retracted/resting position, pressure cylinder body 130 may not abut or touch extending body 160. In the retracted/resting position, frameless lightweight jack 100 is configured to maintain a gap 105 between pressure cylinder body 130 and extending body 160 sufficient to avoid potential pinching, cutting, etc. of fingers, skin, or any part of the body. For example, in some embodiments, gap 105 may be an inch or more. Pressure cylinder body 130 may be mechanically coupled to hydraulic actuators 140 and 141.

Extending body 160 may be coupled to hydraulic actuators 140 and 141. Extending body 160 may be a block of any shape having extending body passage 136 and adapted to receive hydraulic actuators 140 and 141. Hydraulic actuators 140 and 141 may include internal pistons positioned within and collinear with outer cylinders of hydraulic actuators 140 and 141. These pistons may be configured to extend externally in an axial direction upon hydraulic actuation. Operation of hydraulic actuators 140 and 141 is fully described in U.S. Ser. No. 15/596,261. The pistons may be the portion of hydraulic actuators 140 and 141 that are mechanically coupled to pressure cylinder body 130. These pistons may have a smaller diameter as compared to conventional jack designs. For example, in some embodiments, the pistons may have a diameter of 1.12 in or less. The smaller piston diameter may result in a weight reduction as compared with conventional jack designs.

Upon hydraulic activation, the pistons may extend externally thereby causing axial movement of the pressure cylinder body 130 away from extending body 160 (or in the case that pressure cylinder body 130 is fixed, the extending body 160 may more axially away from fixed pressure cylinder body 130).

Hydraulic actuators 140 and 141 may be free floating on the opposite ends distal from where the pistons extend externally and attach to pressure cylinder body 130, as opposed to being attached to a jack frame, as is the case with existing designs. In existing designs, the frame also includes hydraulic fluid port(s) and internal channels for routing hydraulic fluid. The conventional frame design is metal and comprises a substantial portion of the overall weight of the jack. Embodiments of the present disclosure eliminate the frame for substantial weight savings and incorporate a different hydraulic fluid system. According to exemplary embodiments, and as discussed above, lightweight jack 100 may have a single hydraulic fluid connection point at servicing tee 112. Servicing tee 112 may install directly in a hydraulic port 113 of hydraulic actuator 140. This port may be near the distal end, opposite extending body 160, and on the circumferential surface of, hydraulic actuator 140. A cylinder loop hose 115 may also attach to servicing tee 112. Cylinder loop hose 115 may run from the servicing tee 112 to a series of fittings, namely swivel fitting 116 and street elbow 117, that install in a hydraulic port 114 of hydraulic actuator 141. This port may be near the distal end, and on the circumferential surface of, hydraulic actuator 141. Thus, the cylinder loop hose 115 may serve to fluidly connect hydraulic actuators 140 and 141 and to maintain equal pressure between these two actuators. Cylinder loop hose 115 may be routed as illustrated in FIGS. 1, 4, and 5, so as to be compact to hydraulic actuators 140 and 141 and to be shielded by jack handle 190. As a result, Cylinder loop hose 115 of frameless lightweight jack 100 may be protected against getting caught on, or snagged by, anything external such as hands, feet, tension member, etc.

FIG. 2 shows an exploded view of frameless lightweight jack 100. Pressure cylinder 120 connects with pressure cylinder body 130 and incorporates wedge setter 122. This assembly may also include return springs 124. Hydraulic actuators 140 and 141 may be attached to pressure cylinder body 130 with cylinder studs 126. Hydraulic actuators 140 and 141 may also be connected to extending body 160. Location and routing of the hydraulic system is also evident in FIG. 2. For example, servicing tee 112, cylinder loop hose 115, swivel fitting 116 and street elbow 117 are depicted in their relative orientations. Further, jack handle 190 may attach to extending body 160 and provide a way for users to position and move frameless lightweight jack 100.

Lightweight jack 100 may include strand grabber 180. In some embodiments strand grabber 180 may include one or more strand grabber handles 182. Strand grabber 180 be part of a strand grabber assembly including a grabber block 186 and a grabber retaining plate 187. Strand grabber 180 may be positioned inside grabber block 186 and may be fixed in this position by grabber retaining plate 187 that is mechanically attached to the grabber block 186. Grabber block 186 may be mechanically attached to extending body 160. In some embodiments, strand grabber 180 may engage the tension member at grabber block 186. Grabber block 186 may have an inner surface for receiving the tension member. In some embodiments, the inner surface of grabber block 186 may be curved. In some embodiments, grabber block 186 may circumferentially enclose the tension member. In some embodiments, grabber block 186 may partially extend around a circumference of the tension.

Strand grabber 180 may be adapted to engage with a tension member. Strand grabber 180 may engage with a tension member by such non-limiting means as scissoring, springing, or pliering together, thereby holding the tension member in place. Strand grabber 180 may be allowed movement in the axial direction relative to grabber block 186 for the purpose of “grabbing” a tensioning tendon. For example, when a tensioning tendon is installed, the handle of strand grabber 180 may be pulled axially away from the direction of the tensioning tendon. This causes a wedge effect where the tensioning tendon is grabbed and not allowed to move. Upon activation of frameless lightweight jack 100, hydraulic actuators 140 and 141 cause relative axial movement between pressure cylinder 120 and extending body 160. With a tensioning tendon installed, that force tending to cause the relative axial movement may be transmitted to the tensioning tendon via strand grabber 180 and grabber block 186, which hold the tensioning tendon, thereby preventing slipping. The result may be a tensioning force applied to the tensioning tendon by frameless lightweight jack 100.

FIG. 3 shows a front view of frameless lightweight jack 100. As shown in FIG. 3, cylinder body passage 132 and extending body passage 136 are aligned to form tension member channel 138 adapted to receive a tension member.

FIG. 4 shows a top-level view of frameless lightweight jack 100. This view further illustrates position of the hydraulic system of frameless lightweight jack 100 and the relative locations of servicing tee 112, cylinder loop hose 115, swivel fitting 116 and street elbow 117. For example, cylinder loop hose 115 may connect to servicing tee 112, run axially along the outer diameter of hydraulic actuator 140, turn toward hydraulic actuator 141, run under jack handle 190, and axially back down the outer diameter of hydraulic actuator 141 before connecting to swivel fitting 116 and street elbow 117. Further, gap 105 between pressure cylinder 130 and extending body 160 is maintained when frameless lightweight jack 100 is in a retracted/resting position. In exemplary embodiments, gap 105 may be maintained with hydraulic actuators 140 and 141. For example, the internal pistons of hydraulic actuators 140 and 141 may be sized such that they are longer than the external casing or shell of hydraulic actuators 140 and 141. Thus, in the retracted/resting position, the pistons may extend from hydraulic actuators 140 and 141 to maintain a gap 105. In other exemplary embodiments, hydraulic actuators 140 and 141 may include one or more internal stops that limit travel of the internal pistons such that in the retracted/resting position, the pistons of hydraulic actuators 140 and 141 may maintain a gap 105.

FIG. 5 shows a side view of frameless lightweight jack 100. Routing of the hydraulic system and relative positioning according to an exemplary embodiment may evident. Hydraulic actuators 140 and 141 may be free floating, without frame, on a distal end opposite extending body 160. Further, gap 105 between pressure cylinder 130 and extending body 160 is maintained when frameless lightweight jack 100 is in a retracted/resting position.

During operation, frameless lightweight jack 100 may be positioned against a portion of concrete from which a tensioning member extends. This portion of concrete may be a pocket formed within the concrete for the purpose of housing a tensioning member. Pressure cylinder 120 may be inserted against the concrete, or into the concrete pocket so as to position the tension member within tension member channel 138. Wedge setter 122 may abut one or more wedges disposed within the concrete pocked and surrounding the tensioning member. As hydraulic pressure is applied by frameless lightweight jack 100 as described below, pressure cylinder 120 and wedge setter 122 may push the one or more wedges thereby holding the tension member in place.

In applying hydraulic pressure via frameless lightweight jack 100, hydraulic pressure may be applied to pressure cylinder 120 through hydraulic actuators 140 and 141 to move frameless lightweight jack 100 from a retracted position to an extended position.

As discussed, hydraulic actuation may cause the inner pistons of hydraulic actuators 140 and 141 extend, thereby causing extending body 160 to move axially away from the concrete and tensioning member. As extending body 160 moves axially away from the concrete, strand grabber 180 may pull the tensioning member away from the concrete, thereby tensioning the tension member. Hydraulic pressure may be added until a preferred hydraulic pressure is reached. Hydraulic fluid may be extracted from frameless lightweight jack 100 via one or more hoses connected to servicing tee 112.

The foregoing outlines features of several embodiments so that a person of ordinary skill in the art may better understand the aspects of the present disclosure. Such features may be replaced by any one of numerous equivalent alternatives, only some of which are disclosed herein. One of ordinary skill in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. One of ordinary skill in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.

Claims

1. A frameless lightweight jack comprising: a pressure cylinder, the pressure cylinder having a pressure cylinder passage;a pressure cylinder body, the pressure cylinder body being a block through which a pressure cylinder body passage is formed, the pressure cylinder body mechanically coupled to the pressure cylinder;a first and a second hydraulic actuator, the first and the second hydraulic actuator each coupled to the pressure cylinder body on a proximal end, wherein the first and the second hydraulic actuator are in hydraulic communication through a cylinder loop hose connected to a port in a distal end of each of the first and second hydraulic actuator;an extending body, the extending body coupled to the first and the second hydraulic actuator, the extending body being a block through which an extending body passage is formed, wherein the pressure cylinder passage, the pressure cylinder body passage, and the extending body passage are aligned to form a tension member channel; anda strand grabber assembly, the strand grabber assembly mechanically coupled to the extending body;wherein the pressure cylinder, pressure cylinder body, and extending body are comprised of aluminum, titanium, fiber reinforced plastic, polymers, or carbon fiber.

2. The frameless lightweight jack of claim 1, wherein the hydraulic actuators are pneumatically actuated.

3. The frameless lightweight jack of claim 1, wherein the first and the second hydraulic actuator each have an internal piston.

4. The frameless lightweight jack of claim 3, wherein the first and the second hydraulic actuator are each coupled to the pressure cylinder body at a proximal end of the internal piston of each hydraulic actuator

5. The frameless lightweight jack of claim 1, wherein the strand grabber assembly comprises: a strand grabber handle;a strand grabber;a grabber block; anda grabber retaining plate.

6. The frameless lightweight jack of claim 1, wherein the first and the second hydraulic actuator are free floating on the distal ends.

7. The frameless lightweight jack of claim 1, wherein the port in the distal end of each of the first and second hydraulic actuator is on a circumferential surface of each hydraulic actuator.

8. A frameless lightweight jack comprising: a pressure cylinder body, the pressure cylinder body being a block through which a pressure cylinder body passage is formed;a first and a second hydraulic actuator, the first and the second hydraulic actuator each coupled to the pressure cylinder body on a proximal end, wherein the first and the second hydraulic actuator are in hydraulic communication through a cylinder loop hose connected to a port in a distal end of each of the first and second hydraulic actuator;an extending body, the extending body coupled to the first and the second hydraulic actuator, the extending body being a block through which an extending body passage is formed, wherein the pressure cylinder body passage and the extending body passage are aligned to form a tension member channel; anda strand grabber assembly, the strand grabber assembly mechanically coupled to the extending body;wherein the pressure cylinder body is configured to not touch the extending body when the frameless lightweight jack is in a retracted position.

9. The frameless lightweight jack of claim 8, wherein there is a gap between the pressure cylinder body and the extending body when the frameless lightweight jack is in the retracted position.

10. The frameless lightweight jack of claim 8, wherein the gap is at least 1 inch.

11. A method of using a frameless lightweight jack comprising: positioning the frameless lightweight jack in a retracted position so as to abut a concrete structure with a tensioning member, the lightweight jack including: a pressure cylinder body, the pressure cylinder body being a block through which a pressure cylinder body passage is formed;a first and a second hydraulic actuator, the first and the second hydraulic actuator each coupled to the pressure cylinder body on a proximal end, wherein the first and the second hydraulic actuator are in hydraulic communication through a cylinder loop hose connected to a port in a distal end of each of the first and second hydraulic actuator;an extending body, the extending body coupled to the first and the second hydraulic actuator, the extending body being a block through which an extending body passage is formed, wherein the pressure cylinder body passage and the extending body passage are aligned to form a tension member channel; anda strand grabber assembly, the strand grabber assembly mechanically coupled to the extending body;wherein the pressure cylinder body is configured to not touch the extending body when the frameless lightweight jack is in a retracted position;engaging the tensioning member with the strand grabber assembly;moving the frameless lightweight jack from a retracted position to an extended position so as to tension the tension member;moving the frameless lightweight jack from the extended position to the retracted position, such movement resulting in a gap between the pressure cylinder body and the extending body.