US3346890A

US3346890A - Adjustable draw sheet frame and draw sheet

Info

Publication number: US3346890A
Application number: US530126A
Authority: US
Inventors: Adrian J Thompson
Original assignee: Individual
Current assignee: Individual
Priority date: 1966-02-25
Filing date: 1966-02-25
Publication date: 1967-10-17
Anticipated expiration: 1984-10-17

Description

Oct. 17, 1967' A. J. THOMPSON ADJUSTABLE DRAW SHEET FRAME AND-DRAW SHEET 5 Sheets-Shet 1 Filed Feb. 25, 1966 0d. 17, 96 A. J. THOMPSON 3,345,890

ADJUSTABLE DRAW SHEET FRAME AND DRAW SHEET Filed Feb. 25, 1966 5 Sheets-Sheet 2 m N a INVENTOR; AfiE/A/V I flaw/ 50v Q BY I m G Oct 17, 1967 A. J. THOMPSON ADJUSTABLE DRAW SHEET FRAME AND DRAW SHEET 5 Sheets-Sheet 5 Filed Feb. 25, 1966 INVENTOR. ADE/AN J THOMPJDA/ ATEE/I/EWS Oct. 17, 1967 A. J. THOMPSON 3,346,390

ADJUSTABLE DRAW SHEET FRAME AND DRAW SHEET 5 Sheets-Sheet 4 Filed Feb. 25, 1966 INVENTOR. Ape/AM J f /ampsa/v w wE 8d. 1'7, 196? A. .1. THOMPSON 3,346,890

ADJUSTABLE DRAW SHEET FRAME AND DRAW SHEET Filed Feb. 25, 1966 5 Sheets-Sheet 5 INVENTOR. ADE/4N J THGMPSd/V United States Patent Ofihce astssaa Patented Get. 17 1967 ABSTRACT OF THE DISCLOSURE A draw sheet frame with extensible side and end members, the side members being articulated for folding as desired; and a draw sheet with longitudinal reinforcements for anchoring to the ends of the frame, and also tunnel loops at each side receiving the frame therethrough; the sheet also having slots through which extend clamping screws securing draw bars in clamped relation on the sheet and retaining the sheet taut in a transverse direction.

This invention relates to an adjustable draw sheet frame and draw sheet adapted for bedside nursing.

Oftentimes, in bedside nursing, nurses, orderlies and others attending patients must move a patient either from a bed, so that the bed may be changed, or to an alternate position in a bed. This is, typically, a time consuming task as well as a strenuous task. The patient may be large or may have an afl'liction such that moving the patient is very difficult. Further, those charged with the responsibility of moving patients generally do not have uniform procedures for moving patients in order to insure maximum safety to both the patient and the personnel moving the patient.

With these comments in mind it is to the elimination of these and other disadvantages to which the present invention is directed, along with the inclusion therein of other novel and desirable features.

It is an object of this invention to provide a new and improved draw sheet frame and draw sheet of simple and inexpensive construction and operation.

Another object of this invention is to provide a draw sheet frame and draw sheet which may be operated by one with a minimum of manual skill and dexterity as well as with a minimum of strength while providing maximum safety and comfort to the patient when being moved as well as to the operator conducting the move.

It is a further object of this invention to provide an adjustable draw sheet frame and draw sheet which may accommodate various size beds.

It is a further object of this invention to provide an adjustable draw sheet frame which may rest on or be attached to a chair or attached to a mobile frame adapted to receive the draw sheet frame and transport the patient as desired.

A further object of my invention is to provide a draw sheet which may be readily secured to the draw sheet frame and which has sufficient strength to retain the patient when the patient is being moved.

These and other objects and advantages of my invention will more fully appear from the following description made in connection with the accompanying drawings, wherein like reference characters refer to the same or similar parts throughout the several views, and in which:

FIG. 1 is a perspective view showing my draw sheet frame placed on a mattress.

FIG. 2 is a plan view showing my draw sheet attached to my draw sheet frame.

FIG. 3 is a plan view of my draw sheet prior to assembling the draw sheet to the draw sheet frame.

FIG. 4 is an enlarged sectional view taken along the line 4-4 of FIG. 1.

FIG. 5 is an enlarged sectional view taken along the line 5-5 of FIG. 1.

FIG. 6 is a sectional view taken along the line 6-6 of FIG. 4 and along the line 6-6 of FIG. 5.

FIG. 7 is a sectional view taken along the line 7-7 of FIG. 5.

FIG. 8 is a sectional view taken along the line 8-8 of FIG. 4.

FIG. 9 is a sectional view taken along the line 9-9 of FIG. 4.

FIG. 10 is a plan view taken along the line 10-10 of FIG. 4.

FIG. 11 is an enlarged sectional view taken along the line 11-11 of FIG. 3.

FIG. 12 is an enlarged sectional view taken along the line 12-12 of FIG. 2.

FIG. 13 is aside elevation view showing a portion of my draw sheet frame and draw sheet in an upright sitting position attached to a mobile frame.

FIG. 14 is a perspective view showing the detachable cross bar assembly of the draw sheet frame.

One form of the present invention is shown in the drawings and is described herein.

The draw sheet frame of my invention is indicated in general in FIG. 1 by numeral 20. Frame 20 includes a pair of opposed parallel longitudinal members comprising inner tubes 20:: and outer tubes 20b and a pair of 0pposed parallel transverse members comprising inner tubes 20!: and outer tubes 20d. Assembled the tubes form a generally rectangular, adjustable frame. The frame 20 is shown placed on a mattress 21. The frame has been sized in both length and width to correspond to the length and width of the mattress, and the longitudinal and

transverse members

20a and 20b, respectively, rest on the outer upper surface of the mattress 21. Length adjustments are shown at 22 and width adjustments are shown at 23. Apertures 23a receive and secure a draw sheet. The frame is constructed of rigid tubular steel with outer tubing having a nominal diameter of approximately 1% inch and inner tubing correspondingly less diameter to slidably engage the inside of the outer tubin FIG. 2 shows a draw sheet 24 mounted on the draw sheet frame 2%. The draw sheet is constructed of heavy duty cotton muslin with a reinforcement of canvas web. The draw sheet is adapted to fit a variety of draw sheet frames both in length and width. The draw sheet includes a plurality of draw strings or anchoring elements 25 adapted to secure the draw sheet in the longitudinal direction by tying the sheet to the transverse members. or through the draw sheet receiving apertures 23a. The draw sheet includes a plurality of tunnel loops 26 stitched along stitch lines 26a and provided to allow the longitudinal members of the frame 20 to pass therethrough. A plurality of draw bars, indicated by numeral 27 are included to secure the draw sheet 24 to the longitudinal members. Slots 27a are provided to receive draw bars 27.

FIG. 3 shows the draw sheet separate from the frame and shows the reinforcing webbing. Longitudinal webbing 28 may be continuous with draw strings 25 or the draw strings may be affixed to the strips 28. Transverse reinforcing strips are indicated at 29. The longitudinal and transverse reinforcing strips are typically canvas web material stitched to the heavy duty cotton muslin, thereby providing adequate strength to the draw sheet 24. The webs 28 and 29 are about 2 inches wide.

Webs 29 are passed through slits 29a of the draw sheet over loops 26, contacting the upper surface of loops 26, and then through slits 29b to a position supporting the draw sheet at the center portion thereof. The detail of the tunnel loop arrangement and corresponding reinforcing web may be seen in the cross section of FIG. 11. The longitudinal web 28 is shown with the draw sheet 24 thereon. Slots 27a are shown on each side of tunnel loop 26. The reinforcing web 29 is shown on the upper surface of the tunnel loop 26 to provide strength when the draw sheet 24 is secured in the lateral direction.

FIG. 4 shows a portion 20a of the longitudinal member with sleeve assembly 31: over the longitudinal member. The sleeve locks the longitudinal member in place and, when removed, allows a portion of the longitudinal member to pivot upwardly forming a frame having a back rest when the draw sheet is attached. The hinge includes a shaft 31 inserted into tube 20a and welded as indicated at'32, forming a continuous member. Another shaft 33 is weldedinto tube 20a at weld 34. Shafts 31 and 33 are pivotally connected, pivoting about shaft 35 which is generally transverse to the longitudinal member, providing means for pivoting one portion of the frame upwardly about the shaft 35. Referring to FIG. 8, the shaft 35 is shown joining shafts 31 and 33 which are notched to accommodate each other and freely pivot to an upright position. It should be noted that the pivot action is combined to the tube area thereby preventing the pivoted shaft 31 from harming the mattress. The sleeve 30 is slidable on the shafts 31 and 33 and tubing 20a of the longitudinal member and may be moved away from the pivot point allowing the frame to be pivoted about this point to an upright position.

The sleeve includes a spring mounted pivot latch indicated by numeral 36 and shown in a position engaging member 20a. To release the pivot latch, the latch is depressed at 37 and assumes the position 38, indicated by the dotted lines with the latch disengaged from the tubing 20a. The sleeve may now be moved to a predetermined position freeing the shafts 31 and 33 for rotation. The latch engages an aperture 39 in tubing 20a which tubing includes a plurality of apertures 39 to receive the locking mechanism 36. The locking mechanism slides in a grooved track in the tubing. Mounting assembly 40 is assembled to the sleeve 30 with screws 41. FIG. shows the latch 36, mounting bracket 40 and screw 41 on the sleeve 30. The latch 36 is pivotally mounted, pivoting at 36a. It should be noted that the pivot is located substantially in the middle of the frame, and between each set of draw bars. This is done to afford a taut seat portion and a taut back portion when the frame is arranged in the sitting position.

Sleeve 30' is shown on FIG. 1 and is substantially the same as sleeve 30 except that sleeve 30' is sized to fit over the outer tubing 2012.

In FIG. 5, length adjustment 22 is shown and includes a latch for securing the frame length. The latch is similar to latch 36 and is indicated by numeral 42a. It pivots about the axis 43 which is transverse to the frame. The latch is mounted on outer tube b and engages inner tube 20:: at aperture 44 securing the inner tube within the outer tube. The latch i released in the same manner as the latch 36 of sleeve 30, thereby allowing longitudinal movement of the inner tube within the outer tube. The latch is assembled to the outer tube in the same manner as the latch 36 is assembled to the sleeve 30. A support mounting bracket 45 is shown on FIG. 5 and is adapted to receive a supporting member to reinforce the frame portion in the upright position. The width adjustment 23. is the same as the length adjustment 22 and is therefore not discussed.

FIG. 6 shows inner tubing 20a which is similar to inner tubing 20c and which includes a groove portion 46 adapted to receive thesliding latch mechanism 36 or 42. FIG. 6 shows groove 46 which includes upwardly projecting spaced apart side walls 47 adapted to provide a suitable groove for the latch mechanism. The tubing is forced downwardly by a mating die to provide the slot. The groove may also be cut from the tubing. The groove in the outer tubing adapted to receive the sleeve 30' is of the same configuration but placed in the outer tubing.

FIG. 7 shows the relation between the inner tubing 20a and the outer tubing 2017 with the slot 46 in the inner tubing adapted to receive the length adjustment 22. Mounting bracket 45 is shown attached to the outer tubing 2015. FIG. 9 shows a shaft 31 disposed in the sleeve 30 which has the same inner diameter as the inner tubing 20a. The diameter of shaft 31 is substantially the same as the diameter of the inner tubing 20a. Sleeve 30' has an inner diameter adapted to slide over outer tubing 2% which includes a groove to receive the slidable latch mechanism.

FIG. 12 shows a detail of the draw bar which secures the draw sheet to the longitudinal members of the frame 20 providing a taut draw sheet in the transverse direction. Draw bar 27 includes an upper knurled roll 48 and a mating lower knurled roll 49. A pair of thumb screws 50 pass through a pair of threaded receiving portions 51 attached at each end of upper knurled roll 48. A pair of sockets 52 are attached to and disposed at each end of the knurled roll 49. The screws 50 pass through threaded portion 51 and are rotatably mounted in sockets 52 thereby joining the upper roll 48 with the lower roll 49. The upper and

lower rollers

48 and 49 are tightened, utilizing the thumb screws 50 drawing the threaded portion 51 toward socket 52. The draw bar rolls are shown with loop material 26 and the draw sheet 24 therebetween. As shown in FIG. 2, the draw bar is placed outwardly of the longitudinal members with screws 50 disposed through slots 27a. The upper knurled roll 48 is placed in contact with loop 26, and the lower knurled roll 49 is in contact with the sheet material 24. As the width of the frame is decreased, the draw bar is moved inwardly, maintaining its position adjacent the longitudinal frame member and tightened in the predetermined position, maintaining the draw sheet 24 in a taut position in the transverse direction.

FIG. 13 shows the frame 20 in the sitting position and shows the horizontal position in dotted lines. The up-right portion of frame 20 is pivoted about pivot shaft 35 which joins shafts 31 and 33. A patient is shown in both the horizontal position and in the sitting position, the patient indicated in general by numeral 53. A frame support is mounted on brackets 45 maintaining the draw sheet frame in the sitting position. The supporting structure includes a rigid angulated member 54 formed from 1% inch diameter steel tubing. The frame 54 includes an adjustable shaft 55 mounted in frame 54 for slidable.

movement therein. A set. screw 56 secures member 55 in frame 54 at a predetermined position. Member 55 and the. supporting structure 54 are attached to brackets 45 which are secured to the longitudinal frame members. This provides means for alternating the frame and draw sheet from the horizontal position to a sitting position with minimum effort If desired, the draw sheet may be loosened from the frame at the foot end to allow the patients legs to drop down. Before this may be done, however, the draw bars 27 must be secure.

The draw sheet frame is shown in FIG. 13, mounted on a mobile frame 58 for ease in locating the sitting patient within a given area. The mobile frame is constructed of steel tubing of approximately 1 /4 inch diameter. A foot receiving platform 59 is mounted on the cart 58 and is adapted to receive the feet of the patient. The frame, can, rying the patient, may also be placed in a chair while the 1 form. The pair of transverse members 200 and 20d are,

separated at adjustable latch 23. The pair of

longitudinal members

20a and 20b are separated at adjustable latch 22. This frees the angulated inner and outer tubing providing storage of the four right angular parts in a compact unit. When the draw sheet frame is to be used, the parts are arranged on a mattress and assembled. During the assembling of the draw sheet frame, a draw sheet is assembled thereon.

The frame is first sized in the transverse direction in order to rest on the outer, upper surface of the mattress 21. Transverse members 200 and d are slidably adjusted in latch 23 to correspond with the width of the mattress 21. Next, the draw sheet 24 is placed on the mattress 21 and the longitudinal members 20:: and 2% are assembled at latch 22, but only after the longitudinal members have been passed through the pair of tunnel loops 26 which are stitched to each side of the draw sheet 24. The latches 22 are then secured, with the longitudinal member corresponding to the length of the mattress 21 in such a way that frame 20 rests on the outer, upper surfaces of the mattress 21. The tunnel loops are arranged with the pivot 35 between each pair of tunnel loops along the

longitudinal members

20a and 20b.

The draw sheet is then secured to the draw sheet frame. Draw sheet ties may be tied to the transverse members 200 and 20d at each end of the frame thereby securing the draw sheet 24 in the longitudinal direction. Alternately, the draw sheet ties 25 may be inserted through draw sheet apertures 23a for a more positive connection. The draw sheet must now be tightened in the transverse direction. Draw bars 27 are mounted on draw sheet 24 alongside the outside edge of the longitudinal frame members by first separating the knurled rolls 48 and 49 and placing the upper knurled roll 48 on the upper portion of the tunnel loop 26 and the lower knurled roll 49 on the undersurface of the draw sheet 24. The draw bar is then reassemble-d by placing bolts 50 through eyelets 51 on the upper roll 48 and then through slots 27a on each side of the tunnel loop 26. The bolts 50 pass through eyelets 52 on each side of the lower roll and are rotatably secured thereto. After each draw bar has been secured, the draw bars are moved inwardly to a position alongside the outer edge of the longitudinal members of the draw sheet frame 20 and bolts 50 are tightened clamping the tunnel loop 26 to the draw sheet 24. This prevents transverse movement of the draw sheet 24 and provides a taut, secure relation between the draw sheet and the properly sized draw sheet frame. The draw sheet frame now includes a draw sheet which is taut and secure in both the longitudinal and transverse directions. It should be noted that the reinforcing web 29 passes over the tunnel loop 26 providing additional strength at the transverse adjustment.

A patient may now be placed on the draw sheet 24 and, for all practical purposes, experiences the same comfort as provided by a bed with a conventional sheet covering. The draw sheet 24 may, of course, be laundered in the conventional manner and is designed for quick changing at predetermined intervals. When it is desirable to move the patient, the draw sheet frame may be grasped and the patient quickly and readily moved with a minimum of discomfort and maximum of safety to the patient as well as maximum safety for the operator.

If it is desired to place the patient in a sitting position, the operator need only grasp latches 36 on sleeves and 30, slidably moving

sleeves

30 and 30 away from pivot 35. The frame is now free to pivot and may be raised, pivoting about pivot 35, without damaging the mattress 21 upon which the frame 20 rests. Since the tunnel loops and draw bars are disposed on each side of the hinge, the draw sheet is taut, properly supporting the patient in a sitting position.

After the patient has been placed in a sitting position, the patient may be moved to a chair to await performance of the task which necessitated moving the patient from the bed. The frame may be reinforced, in the sitting position, with the bracing structure 54 and the interconnecting member 57. The bracing structure provides a slidable adjustment 55 and locking set screw 56 providing a secure sitting position as well as secure positions intermediate the sitting position and the horizontal position of the draw sheet frame. If desired, the draw sheet frame 20 may be mounted on a mobile cart 58 which serves as a means to quickly and readily move the patient from one location to another. Draw strings 25 at the foot end of the frame may be loosened to allow the patient to drop his legs in the sitting position if desired. Since the draw bars 27 art taut in a transverse direction, the patient is still properly supported in the sitting position even though foot end draw strings 25 are loosened.

When not in use the draw sheet frame may be quickly disassembled since the longitudinal and transverse members are slidably engaged in each other and releasably secured by locking mechanisms 22 and 23 respectively. The supporting structure may also be disassembled and stored.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the various parts without departing from the scope of my invention.

What is claimed is:

1. A draw sheet for bedside nursing suitable to support a patient, said draw sheet adapted to be secured to a draw sheet frame having a pair of adjustable longitudinal members and a pair of adjustable transverse members connected to the longitudinal members forming a substantially rectangular frame, said draw sheet compris a sheet member of flexible, yieldable material,

a plurality of longitudinal tie elements aflixed to said sheet member, said tie elements adapted to secure said sheet member to the pair of transverse members of the draw sheet frame whereby the draw sheet is substantially taut in the longitudinal direction,

' a plurality of loop means afiixed to said sheet member in predetermined positions, said loop means adapted to receive the longitudinal members of the draw sheet frame,

a plurality of longitudinal reinforcing strips afiixed to said sheet member, each reinforcing strip having a longitudinal element extending therefrom,

a plurality of transverse reinforcing strips aflixed to said sheet member and draw bar means adapted to clamp said tunnel loops generally longitudinally along and adjacent the outside of the longitudinal members of the draw sheet frame, whereby said draw sheet is substantially taut in the transverse direction.

2. The draw sheet of claim 1 wherein,

said sheet member includes transverse elongate slots of predetermined length disposed alongside the trans verse edges of each of said tunnel loops,

said draw bar means includes,

an upper roller adapted to contact said tunnel loop,

a lowler roller adapted to contact said sheet member,

adjustable connecting means adapted to pass through the transverse slots in said sheet member and connect said upper and lower rolls whereby said rolls may be tightened securing said tunnel loop to said sheet member along a predetermined longitudinal area adjacent the outside of each draw sheet frame longitudinal member thereby maintaining said draw sheet substantially taut in the transverse direction.

3. A draw sheet frame and draw sheet for bedside nursing suitable to support a patient, said draw sheet frame and draw sheet comprising, in combination,

a pair of opposed, parallel longitudinal members, each longitudinal member having an inner tube of a predetermined outer diameter and an outer tube of a predetermined inner diameter adapted to receive the inner tube for slidable movement therein,

a pair of opposed parallel transverse members each transverse member having an inner tube of a predetermined outer diameter and an outer tube of a predetermined inner diameter adapted to receive the inner tube for slidable movement therein, said transverse members connected to said longitudinal members in right angular relation forming a substantially rectangular frame,

means adjusting the length. of said pair of longitudinal nect said upper and lower rolls whereby said rolls members said means interposed in each of said pair may be tightened securing said tunnel loops to said of longitudinal members, sheet member along a predetermined longitudinal means adjusting the width of said pair of transverse area adjacent the outside of each draw sheet frame members said means interposed in each of said .translongitudinal member thereby maintaining said draw verse members, 10 sheet substantially taut in the transverse direction. asheet member of fiexible,.yieldable material, 6. The draw sheet frame and, draw sheet of claim 4 a plurality of longitudinal tie elements afliXed to said wherein,

sheet member, said tie elements secured to said pair said draw sheet frame is adapted to be mounted on a of transverse members whereby said draw sheet is mobile cart. substantially taut in the longitudinal direction, 7. A draw sheet attachable to a rectangular draw sheet frame having rigid and interconnected longitudinal and transverse frame members, the draw sheet having a corresponding rectangular shape, the ends of the draw sheet having anchor elements attachable to the transverse ends of the frame,

a plurality of loop means affixed to said sheet member in predetermined positions, sandwiching each said longitudinal member between said loop means and said sheet member, and

means securing said loop means to said sheet member adjacent said longitudinal members whereby said sheet member is substantially taut in the transverse direction.

4. The draw sheet frame and draw sheet of claim 3 in and draw sheet to be raised to a substantially upright position, pivot locking means adapted to engage said pivot means the improvement comprising, the sides of the draw sheet having a plurality of transverse slots therein,

and means securing the sheet at each side to the lon-.

cluding, gitudinal member of the frame and including at each pivot means interposed in each of said pair of longitu- Side a rigid bar along the longitudinal frame member dinal members substantially at the midpoint thereof and extending between adjacent Slots, the bar lying whereby a portion f id longitudinal members may against the sheet for maintaining tautness and havpivot about an axis transverse to said longitudinal ing rigid Securing elemfints p l g through the members allowing a portion ofsaid draw sheetjframe slots to COOPBFK'EC With the Shefit a ar t maintain the sheet in predetermined relation to the longitudinal frame member in a transverse direction. 8. The invention according to claim 7 and also including a plurality of elongate and transversely extending reinforcing elements affixed to the sheet, the rigid bar at each side of the frame retaining against the sheet and said reinforcing elements to maintain the sheet in taut condition in a transverse direction.

whereby said pivot means is locked in a predetermined position,

a pair of tunnel loops afiixed to said sheet material on each side thereof adapted to receive each longitudinal member, said tunnel loops having a substantially right angular configuration and afiixed along lon- References Cited gitudinal edges to said sheet member, said pair of 40 tunnel loops having said pivot means disposed there- UNITED STATES PATENTS between, and draw bar means adapted to maintain said tunnel loops 2??? 323 5;; in contact with said sheet member, the contact area 1 323257 12/1919 Dudek 5 183 generally longitudinal and adjacent the outside of 2242311 5 /1941 Lucey each of said longitudinal members whereby said draw 2544977 3/1951 Blank sheet is substantially taut in the transverse direction. 2960701 11/1960 Nawar; 115. The draw sheet frame and draw sheet of claim 4 3:O39:119 6/1962 g w erem, u

said sheet member includes transverse elongate slots of FOREIGN PATENTS predetermined length disposed alongside the trans- 581,318 8/1958 Italy.

verse edges of each of said tunnel loops, and said draw bar means includes, an upper roller adapted to contact said tunnel loops,

CASMIR A. NUNBERG, Primary Examiner.

Claims

3. A DRAW SHEET FRAME AND DRAW SHEET FOR BEDSIDE NURSING SUITABLE TO SUPPORT A PATIENT, SAID DRAW SHEET FRAME AND DRAW SHEET COMPRISING, IN COMBINATION, A PAIR OF OPPOSED, PARALLEL LONGITUDINAL MEMBERS, EACH LONGITUDINAL MEMBER HAVING AN INNER TUBE OF A PREDETERMINED OUTER DIAMETER AND AN OUTER TUBE OF A PREDETERMINED INNER DIAMETER ADAPTED TO RECEIVE THE INNER TUBE FOR SLIDABLE MOVEMENT THEREIN, A PAIR OF OPPOSED PARALLEL TRANSVERSE MEMBERS EACH TRANSVERSE MEMBER HAVING AN INNER TUBE OF A PREDETERMINED OUTER DIAMETER AND AN OUTER TUBE OF A PREDETERMINED INNER DIAMETER ADAPTED TO RECEIVE THE INNER TUBE FOR SLIDABLE MOVEMENT THEREIN, SAID TRANSVERSE MEMBERS CONNECTED TO SAID LONGITUDINAL MEMBERS IN RIGHT ANGULAR RELATION FORMING A SUBSTANTIALLY RECTANGULAR FRAME, MEANS ADJUSTING THE LENGTH OF SAID PAIR OF LONGITUDINAL MEMBERS SAID MEANS INTERPOSED IN EACH OF SAID PAIR OF LONGITUDINAL MEMBERS, MEANS AJDUSTING THE WIDTH OF SAID PAIR OF TRANSVERSE MEMBERS SAID MEANS INTERPOSED IN EACH OF SAID TRANSVERSE MEMBERS, A SHEET MEMBER OF FLEXIBLE, YIELDABLE MATERIAL, A PLURALITY OF LONGITUDINAL TIE ELEMENTS AFFIXED TO SAID SHEET MEMBER, SAID TIE ELEMENTS SECURED TO SAID PAIR OF TRANSVERSE MEMBERS WHEREBY SAID DRAW SHEET IS SUBSTANTIALLY TAUT IN THE LONGITUDINAL DIRECTION, A PLURALITY OF LOOP MEANS AFFIXED TO SAID SHEET MEMBER IN PREDETERMINED POSITIONS, SANDWICHING EACH SAID LONGITUDINAL MEMBER BETWEEN SAID LOOP MEANS AND SAID SHEET MEMBER, AND MEANS SECURING SAID LOOP MEANS TO SAID SHEET MEMBER ADJACENT SAID LONGITUDINAL MEMBERS WHEREBY SAID SHEET MEMBER IS SUBSTANTIALLY TAUT IN THE TRANSVERSE DIRECTION.