TW201036575A - Assembled bed - Google Patents

Abstract

An assembled bed includes two lateral rods each having a first length; two terminal rods each having a second length; four connection members each having two inserting holes respectively extending in first and the second directions; and a supporting layer comprising two lateral sleeve parts extending in the first direction and two terminal sleeve parts extending in the second direction. Each inserting hole has a small-diameter section and a large-diameter section. For each connection member, the first space is defined from one end of the small-diameter section of one inserting hole to a central line of another inserting hole in the first direction, and a second space is defined from one end of the small-diameter section of another inserting hole to a central line of the other inserting hole in the second direction. Axial lines of the terminal sleeve parts and the lateral sleeve parts are respectively spaced by first and second distances in the first and the second directions, and the first distance and the second distance are respectively equal to the first length and the second length plus two times of the first space and the second space. The lateral rods and the terminal rods are respectively sleeved in the lateral sleeve parts and the end sleeve parts of the supporting layer. When the lateral rods, the terminal rods and the connection members are assembled to form a bed frame, the supporting layer is tightly installed on the bed frame.

Description

201036575, VI, invention description: [Technical field of the invention] The present invention relates to a type of bed, in particular to a combined bed 0 [Prior Art] As shown in Fig. 1, a conventional combination The bed (U.S. Patent Publication No. 634.B2) comprises two side rods 2 end rods 2 'four joint pieces 3 and one bed net 4, and each of the connecting pieces 3 has two for each side rod U therein - an insertion hole 3 〇 1 inserted in the end rod 2 - the bed net 4 has a two-side sleeve portion 4 〇 1, an end-through sleeve portion 402, and a detachable movable sleeve portion 403 having a movable sleeve portion 403 A male adhesive fastener 4〇4, and a female adhesive fastener 4〇5 (ie, Velcro). Thereby, the user can put the side rods 1 and the one end rod 2 on the side sleeve portions 4〇1 and the end sleeve portions 4〇2, and the side rods! The end rods 2 are combined with the connecting members 3 to form a frame 5, and finally the female fastening members 405 are pulled around the other end rods 2 and fastened to the male fastening members 404, thereby making the bed The network is tight. Ο However, in the continuous assembly, the user must erect the frame 5 on the ground, and forcefully pull the female fastening member 4〇5 closer to the male fastening member, 404, so that it is difficult for the user. The female adhesive member 4〇5 is evenly adhered to the male adhesive fastener 404, so that the bed net 4 cannot be evenly stretched; in addition, the male adhesive fastener 404 is extremely easy to adhere to the dander, which is not only difficult. Clean and affect the fixing effect of the fastener. In addition, it is known that a structural improvement of a child's bed (Taiwan New Patent Application No. 91201983) is provided with a positioning surface of the foot and an end portion 3 201036575 of the strut, and a flat surface which is positioned to prevent rotation and is prevented from rotating. In order to prevent the rotation of the strut, however, the design of the mesh body is as in the above-mentioned U.S. patent, and it is also necessary to use the devil blanket to fix the positioning and adjust the tension, and therefore, the same defect is also generated. In addition, a combination of a convenient bed structure (Taiwan New Patent Application No. 9_8649) and another type of multifunctional baby bed (Taiwan New Patent Application No. 86218756) are used in the bed net. A sleeve portion is disposed on each of the two sides and one end thereof for allowing the two side rods to pass through the one end rod and extending at the other end of the bed net - an extension portion having a plurality of positioning holes for transmitting the extension portion The user is required to continuously wind the extended section by the other end rod, and laboriously combine the other end rod with the bed angle on the side rods. From the beginning, only the warehouse _ into assembly work. Such beds are not only complicated in manufacturing, but also: the user is quite numb in the assembly operation. In addition, the bed net needs an extra length of extra length to increase the manufacturing cost. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a combined bed which can be evenly tightly packed in a bed net. The other purpose of this month is to provide a combined method for a combined bed that is convenient for grouping. It is a combined bed of the present invention comprising two side bars, two end bars, four and a selective layer. The side bars each have a first length. The i^ rods respectively have a first length of the first-county g-page. The connecting members respectively have a insertion hole extending along a first direction, and a insertion hole extending in a direction perpendicular to the first direction of the 201036575 • a connecting hole for each of the connecting members respectively One of the rods and the end rods are detachably inserted, the insertion holes of each of the connecting members respectively have a small aperture section, and a large aperture extending outward from the small aperture section and having a larger aperture than the small aperture section a segment, one end of the small aperture section of one of the insertion holes of each connector along the first direction to the "center line t of the other insertion hole - the first-pitch" of the other small aperture of the insertion hole Between the first direction and a center line of one of the insertion holes, the 支撑 帛 spacing a support layer has two sides spaced along the second direction and extending along the first direction respectively a sleeve portion, and two end-sleeve portions that are spaced apart in the first direction and respectively extend along the second direction, the side-through sleeve portions are detachably worn for the side rods, and the end portions are sleeved The end portions are respectively detachably worn, and the end end sleeve portions respectively have a corresponding The axes of the end sleeves are spaced apart from the first direction by a first distance 'the first distance' a spacing, the side sleeves respectively having an axis corresponding to a centerline of the two masts, the axes of the side sleeves being spaced along the second direction - a second distance 'the second distance substantially And the second length is equal to the second distance, wherein the side rods and the end rods are respectively sleeved on the side sleeve portion and the end sleeve portion of the support layer, and the side rods are When the rod is combined with the connectors into a frame, the support is applied to the frame. The combination method of the moon, and the 5-bed bed comprises the following steps: (A) = the equilateral rod and the end rods are respectively sleeved on the side sleeve of the support layer so that the middle side of the crucible and one end thereof The rod and the two of the connector sets 5 201036575 are combined into a first half frame, the end bar is connected between the connecting members, and the other side bar, the other end bar and the other two connecting members are combined into a second half The frame is connected between the connecting members, and the side sills of the first and second half frames respectively have a first insertion end extending outward. (8) reversely twisting the first and second half frames to be non-parallel to each other, so that the first insertion end portions of the side bars of the first and second half frames respectively extend into the insertion of the connecting members of the second and half frames In the large hole control section of the hole, the first insertion end portion and the insertion hole of the insertion hole are at an angle. (8) Reverse the first and second halves in a direction opposite to the step (b)

Torsion to each other horizontally, so that the first insertion ends of the side bars of the first, -4r_ &, L half frame are respectively embedded in the small aperture segments of the insertion holes of the connectors of the second and half frames 'Forming a frame' and then tensioning the floor to the frame. The above and other technical contents, features and effects of the present invention will become apparent from the following detailed description of the preferred embodiments. Referring to Figures 2 and 3', a preferred embodiment of the modular bed of the present invention comprises: two side bars 10, two end bars 20, four connectors 3〇1, 3 0 Π, 3 0 Μ , 30IV, and one side of each side of the pole 10 has two first-standard end portions 11, - a first rod section 12 connected between the first-inserted end portions 11, and two recessed in the respective The first recessed hole i 3 of the first insertion end portion 11 and a first length L1 extending along the _ first direction X. Each of the end rods 2 has two second insertion ends 21, and a second rod segment 22 connected between the second insertion ends 21 and two are respectively recessed in the second 201036575

The second recess 23 of the end portion 21 is inserted perpendicular to the first direction X, and the second length L2 of the edge extends in the second direction Y2. Each of the connecting members 30 I, 30Π, 30, 30IV has a top wall 31, a peripheral wall 32 extending downwardly from the periphery of the top wall 31, and a lower surface extending from the top surface of the top wall 31 below the peripheral wall 32 and defining a surrounding wall 33, two insertion holes 35, and two of the stacking chamber 34 extending through the top wall are respectively disposed on

The first bump 36 in the insertion hole 35 and the second bump 37 disposed in each of the insertion holes 35 at equal angular intervals. Inserting holes 35 for each of the connecting members 30, 3, 30, and 30 IV are formed in the peripheral wall 32 and extend in the first and second directions X and γ, respectively. Each of the connecting members 3GI, then the 'seven, the clearing hole ^ can be detachably inserted into the eight middle side sill 10 and one of the end rods 20, respectively, and each has a small hole 351 351, one from the small aperture The segment 351 extends outwardly and has a larger aperture than the large aperture section 352 of the small aperture section 351, and a slanted guide shoulder 353 that engages between the large and small aperture sections 352, 351. In the present embodiment, the cross-sections of the large and small aperture sections 352, 351 of the interposing π holes 35 of each of the connecting members 3〇I, 3〇11, 3〇羾 are circular, non-circular, respectively. A connecting member 30 1 , 30 Π , 30 瓜 , 30 IV of the first protruding block 36 is disposed at a permanent end of the small aperture section 每一 of each of the insertion holes 35 and has a non-circular cross section, and each connecting member 30 The first bumps 37 of I, 30 Π, 30 Π, 30 are respectively disposed in the large aperture segments 352 of each of the insertion holes, and the cross section of the first insertion end portion 11 of each side bar (7) corresponds to The small aperture section 351 of the side insertion hole 35 is non-circular, and can be embedded in the small aperture section 351, and the outer diameter of the first rod section 12 of each side rod 1〇 is not larger than the insertion hole of the 2010. The aperture of the large aperture section 352 can be embedded in the large aperture section 352 and is in contact with the second protrusions 37. The cross section of the first recessed hole 13 of each side rod 1〇 corresponds to the first protrusions The block 36 is non-circular, and the first protrusions 36 are embedded, and the cross section of the second insertion end portion 21 of each end rod 2 is corresponding to the small aperture section 351 of the insertion hole 35. Shape, which can be embedded In the aperture section 351, the outer diameter of the second rod section 22 of each end rod 20 is not larger than the aperture of the large aperture section 352 of the insertion hole 35, and can be embedded in the large aperture section 352, and the second convex portion The block 37 is in contact with each other, and the cross section of the second recess 23 of each end bar 2 对应 corresponds to the non-circular shape of the first bumps 36, and the first bumps 36 can be embedded. Preferably, the cross-sectional outer contour of the first insertion end 11 of each side rod is rectangular, and the first recess 13 of each side rod 10 has a rectangular cross section, and each end rod 2 is The cross-sectional outer contour of the second insertion end portion 21 is rectangular, and the second recessed hole 23 of each end rod 2 has a rectangular cross section, and the cross section of the small aperture section 351 of the insertion hole 35 of each of the connecting members 30 In a rectangular shape, the cross-sectional outer contour of the first projection 36 of each of the connecting members 3 is rectangular. In this embodiment, the end of the small aperture section 351 of one of the insertion holes 351, 3〇, I, 3〇m, 3〇jv is inserted in the first direction to the other insertion hole. A first spacing center is defined between a centerline of the 35, and an end of the small aperture section 351 of the other insertion hole 35 is defined along the second direction γ to a center line of the one of the insertion holes 35 A second pitch is out. The side support layer 40 has two side-through sleeve portions 41 which are spaced apart in the second direction γ and extend along the first direction X, respectively, and are spaced apart along the first direction and are respectively extended along the second direction γ. The end sleeves, and the diagonal 201036575 line 43, the side sleeves 41 are respectively detachably slidable for the side sills, and the end sleeves 42 are respectively available for the end rods 2 〇 detachably worn. In the present embodiment, the support layer 40 is a bed net. A preferred embodiment of the combined method of the combined bed of the present invention comprises the following steps: Step (A): As shown in Figures 4 and 5, the side bars 1〇 and the end bars 20 are respectively sleeved in the same The side through sleeve portion 4 ι of the support layer 4 与 and the end through sleeve portion a are such that one side rod 10 , one end rod 2 〇 and one of the two connecting members 3 〇 ι : 30π are combined into a first half frame 1 〇〇, and The other side rod 10, the other end of the stem 20 and the remaining two connecting members 3 〇 π, 3 〇Ι γ are combined into a second half frame 2 (9). At this time, the end rod 2〇 of the first half frame 1〇〇 is connected between the connecting members 1 30Π, and the end rod 2 () of the second half frame is connected to the connecting members 30ΙΠ, 3〇. Between the two ends 胄u of the end rods 2〇, the first direction γ is embedded in the connecting member 3〇, and the small aperture section 351 β of the fine, 3 clear insertion hole 35 The two ends of the second rod section 2 of the end rods 20 are embedded in the second direction γ to insert the connecting members, and the large aperture sections 352 〇 of the insertion holes 35 of the 3〇DI, qing, the connection The first bumps 36 of 3〇3〇π and 3〇m, 3〇ιν are respectively embedded in the second recessed holes 23 of the equal-end rods 2G along the second direction γ; and, the first and second halves (10) One of the first insertion ends of the side bars 10 is respectively embedded in the small aperture section 351 of the insertion holes 35 of the connecting members 30 Ϊ, 3〇m along the _ direction X, which is 4 Θ. One end of the first pole segment 12 of the 荨 扣 10 is respectively embedded in the first direction X, and is inserted into the insertion hole 35 of the 荨 connector 301, 3 〇 m. The first bump of the piece 30 I, 30 36 36 points 9 201036575 wherein x fitted such side bars 13 'of the rod 10 the other side of such first end portion inserted respectively located such Shushu connecting member 30H, 30IV than a first holes 10. Step (Β): as shown in FIGS. 6, 7, and 8, the first and second half frames 1 and 200 are reversely twisted around the diagonal 43 of the support layer 4 (see FIG. 5) to each other. Parallelly, the other first insertion ends η of the side bars 1〇 are respectively inserted into the large aperture segments 352 of the insertion holes 35 of the connecting members 30Π, 30IV, at this time, the first insertion end The portion 11 is at an angle θ with the center line of the insertion hole 35. It should be noted that when the first and second half frames 1 〇〇 and 2 〇〇 are reversely twisted, since the connecting members 30 I and 30 IV are lower than the former and the latter is raised relative to FIG. 5 , In FIG. 7, the distance between the connecting members 3 and the shells will be increased compared with FIG. 5, and the aperture of the large aperture section 352 of the insertion hole 35 of the connecting member is larger than the first half frame 1 The outer diameter of the first insertion end portion 11 of the side rod (7) of the crucible, so that the first insertion end portion U can be smoothly assembled into the large aperture section 352 of the insertion hole 35 of the connecting member 3〇IV. Similarly, since the connecting members 30 Π, 30 m are in a state in which the former rises and the latter decreases relative to FIG. 5, the distance between the connecting members 3GII and 30 will also be the same in FIG. Figure 5 is added and can produce the same effect. Step (C): as shown in FIGS. 9, 10 and 11, the first and second halves 100, the diagonal 43 of the support layer 40 (see FIG. 5) are opposite to the step (B). The direction is reversed to the mutual horizontal level 'the other side-interposing end U of the side rods respectively enters the small aperture section of the insertion hole 35 of the connecting members 30Π, 30IV in the first direction , in the slave 351, and the other end of the first rod section 12 of the side rod 10 is embedded in the large diameter of the insertion hole 35 of the connector 10, the 365, the 黯, respectively, along the first universal X In the segment 352, the first-bumps 36 of the connecting members and the slabs are respectively slid in the first direction: into the other first recessed holes 13 of the side bars ί0, and the two frames are combined into a frame. Hey. At the first and second times, as shown in FIG. π, the end of the supporting layer 4〇 passes through the sleeve to have an axis 421, ^ corresponding to the -t core of the end rod 2〇, etc. The drawing line 421 > VL Ma Di early u / mouth. Hai's first direction x interval one _

The first distance D1 is substantially equal to the first length u of the side bars plus twice the first spacing dl, and the side through sleeves 4 of the support layer 4 have - corresponding to the side bars 10 An axis of a centerline is 4 ιι, the axis 411 of the side-through sleeve portion 41 is along the second square _D2, and the second distance D2 is a real distance-length L2 plus twice the one-zero, thus ' The support layer 40 will naturally stretch evenly over the frame 300. Through the above description, the advantages of the present invention can be further summarized as follows: In the actual assembly of the present invention, the user only needs to reversely twist the first and second half frames 1 to 200 to be non-parallel to each other, and The first insertion end portion /1 of the side bar is inserted into the contact hole 35 of the connecting members 3GIV, 3 () li, respectively, and then the second half and the second half frame 100, 200 are twisted back to the horizontal state, that is, The first and second half frames 100, 200 can be combined into the frame 300; at the same time, the branch layer 4 is naturally evenly end to the frame 300, so that the present invention is not only assembled compared to the S head technology. Conveniently, the support layer 4〇 can be effectively tightened, and the side through sleeve portion 41 and the end through sleeve portion 42 of the branch floor do not have the problem of adhering to the shavings. 11 201036575 The above-described combined bed of the present invention is not only convenient for the user to assemble, but also can evenly tighten the bed net, so that the object of the present invention can be achieved. The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, that is, the simple equivalent change of the patent application scope and the description of the invention. The repairs are still within the scope of the invention patent.

12 201036575

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a conventional combination of a combined bed; Fig. 2 is a schematic view of the combined sleep of the present invention;

Figure 3 is a schematic partial cross-sectional view of one side of the preferred embodiment of the preferred embodiment of the preferred embodiment of the preferred embodiment of the preferred embodiment of the preferred embodiment of the present invention. ^ 々忐 々忐 刼 不 δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ δ The middle side rod of the preferred embodiment, the one end rod and the two connecting pieces are combined into a first half frame, and the other side rod and the other end rod of the preferred embodiment are combined with the other two connecting pieces. Figure 6 is a schematic view of the right side of Figure 5, illustrating that the first and second half frames are twisted around the diagonal of the branch floor to be non-parallel to each other, so that the side of the (four) one and two half frames The rods respectively extend into a large aperture section of an insertion hole of the second, half-frame connector; FIG. 7 is a left side view of FIG. 6; FIG. 8 is a view similar to FIG. The side bars of the two half frames respectively extend into the large aperture section of the insertion hole of the second, half frame connector; FIG. 9 is a view similar to FIG. It is stated that the diagonal lines of the first and second half frames around the branch floor are reversely twisted to be horizontal to each other in a direction opposite to the direction of FIG. 7, so that the side bars of the first and second half frames are respectively embedded in the second and half. The frame of the 13 201036575 connector is inserted into a small aperture section of the connector to form a frame; Figure ίο is a view similar to Figure 8 illustrating the side of the first and second half of the frame for the 肷 肷A small aperture section of the insertion hole of the connector of the one-half frame; and Figure 11 is a plan view showing the combination of the preferred embodiment, showing that the support layer is stretched on the frame. 14 201036575

[Description of main component symbols] 10... ...side bar 41 ••... •...lateral insertion sleeve 11...first insertion end 411...-axis 12...first segment 42· . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100... •...first half frame 22......second pole segment 200...•...second half frame 23...the second recessed hole 300...•...frame 30 I ·· ...connecting piece X... 30Π · ...connector Y... •...second direction 30ΠΙ ··...connector L1···.....·first length 30IV ··...connector L2··..·...second Length 31... top wall dl ·...· •...first spacing 32......circumference wall d2······...second spacing 33......around wall D1 ........first distance 34... ...stack space D2...·•...second distance 35... ...interpolation hole θ ····.•...angle 351 ····...small aperture section 352 ····large aperture section 353 · ··· ...guide slip shoulder 36 ... Ti ... bump 37 ... ...... ... ...... second bump 40 support layer 15

Claims (1)

201036575 VII. Patent application scope: 1. A combined bed comprising: · two side rods respectively having a first length; two end rods respectively having a second length; four connecting pieces each having a first a insertion hole extending in a direction, and an insertion hole extending along a second direction perpendicular to the first direction, wherein the insertion holes of each of the connecting members are respectively detachably inserted into one of the rods and one of the rods The insertion holes of each connecting member respectively have a small aperture section, and a large aperture section extending outward from the small aperture section and having a larger aperture than the small aperture section, and one of the connecting members is inserted into the aperture One end of the small aperture section defines a first spacing between the first direction and a centerline of the other insertion aperture, and an end of the small aperture section of the other insertion aperture is along the second direction to the middle a second spacing is defined between a centerline of an insertion hole; and a support layer having two side-through sleeves spaced along the second direction and extending along the first direction, and two along the first One direction interval and respectively along the second side Passing the sleeves to the extended ends, the side sleeves are respectively detachably pierced by the side rods, and the end sleeves are respectively detachably pierced by the end rods, and the end sleeves are respectively slidably disposed Having an axis corresponding to the - centerline of the end rods, the axes of the end sleeves are spaced along the first direction by a first distance, the first distance being substantially equal to the first length plus two The nth of the side-through sleeve portions respectively have a lower edge along the second side direction corresponding to the side rods mm and a second distance 'the second distance is substantially equal to the second length And double the second spacing; 16 201036575 wherein the side rods and the end rods are respectively sleeved on the side sleeve portion and the end sleeve portion of the support layer, and the side rods, the ends When the rod is combined with the connectors into a frame, the support layer is stretched over the frame. 2. The combined bed according to the invention of claim 2, wherein the cross-faces of the large and small aperture segments of the insertion holes of each connector are circular and non-circular, respectively, each connector The insertion hole further has a sliding shoulder that is connected between the large and small aperture segments and has an inclined shape. The combination bed according to claim 2, wherein each side bar has two first insertion ends, and a first rod connected between the first insertion ends The cross section of the first insertion end of the segment, such as Xiao, corresponds to the small aperture section of the insertion hole being non-circular, and the outer diameter of the first rod section is not larger than the aperture of the large aperture section of the insertion hole, and each end rod Having two second insertion ends, and a second rod segment connected between the second insertion ends, the cross sections of the second insertion ends corresponding to the small aperture segments of the insertion holes are non- Circular, the outer diameter of the second rod section is not larger than the diameter of the large aperture section of the insertion hole. 4. The combined bed according to claim 3, wherein each of the connecting members further has two first convex portions respectively disposed at the ends of the small aperture segments of the insertion holes and having a non-circular cross section. Each of the side bars further has two first recesses respectively recessed in the first insertion ends, and the cross sections of the first recesses correspond to the first protrusions being non-circular, each The one end rod further has two second recesses respectively recessed in the second insertion ends, and the second recesses have a cross section corresponding to the first protrusions being non-circular. 5. The combined bed according to claim 4, wherein the cross-sectional outer contour of each of the first insertion ends of the side bars of each of the 17 201036575 is rectangular, and the cross-section of the first recessed holes on each side The cross section is rectangular, the outer surface of the second insertion end β of each end rod is rectangular, and the cross section of the second recess of each __ end rod is rectangular, and the small aperture of the insertion hole of each connecting piece The cross section of the segment is rectangular. The cross-sectional outer contour of the first bump of each connector is rectangular. 6. The combined bed of claim 4, wherein each of the connecting members further has a plurality of second projections spaced apart from each other in the large aperture section of each of the insertion holes. According to the combination of the patents, the cofferdam, wherein each of the connecting members further has a top wall, a wall extending downward from the periphery of the top wall, and a top wall from the top of the top wall. The surrounding soil extending downward to the surrounding wall defines a stacking space extending through the top wall, and the insertion holes of each connecting member are respectively formed on the peripheral wall. According to Shen. The combination method of the combined bed according to the above-mentioned patent scope includes the following steps: (A) the side rods and the end rods are respectively sleeved on the side sleeve and the end sleeve of the support layer a portion, wherein one of the rods, one of the rods and the connecting member thereof are combined into a first-half frame, the end rod is connected between the connecting members, and the other side rods and the other end rods are The remaining: the connecting member is combined into a - a half frame, the end bar is connected between the connecting members, the side bars of the first and second half frames respectively have a first-inserted end extending outward; B) The first and second half frames are reversely twisted to be non-parallel to each other, so that the first insertion end portions of the side bars of the half frame extend into the insertion holes of the connecting members of the second and half frames respectively. In the large aperture section, the first subtraction portion 18 201036575 is at an angle to the center line of the insertion hole; and (C) the first and second half frames are reversely reversed in a direction opposite to the step (β). Leveling each other so that the first insertion ends of the side bars of the first and second frame are respectively inserted into the insertion holes of the connecting members of the second and half frames = in the control section, and form a frame, so that the support layer ends tightly to the frame 9. According to the combination method described in the scope of the patent application, Ο step (B), will be 兮筮,,. In the reverse direction of 0 Hz, the diagonal of the H-cut layer is turned to be non-parallel to each other. In this step (C), half of the material that surrounds the support layer and the ground is broken.镰... The line is reversed to the mutual level in the opposite direction to the direction of step (B). 19