Gas-Cylinder Retaining Assembly

p-0002The present invention relates to a gas-cylinder retaining assembly for a harness for breathing apparatus, in particular, a gas-cylinder retaining assembly including a retaining buckle.

p-0003Self-contained breathing apparatus (SCBA) harnesses comprise a structural support member in the form of a back plate (or frame) to which a cylinder of breathable gas is mounted. The cylinder of gas is retained on the back plate using a flexible cylinder-retaining strap that is attached to the back plate and tensioned around the cylinder. A tensioning device is provided in order to tighten the strap around the cylinder and to maintain the tension in the strap. Depending on the size of the cylinder, a free, surplus portion of the strap usually extends from the tensioning device. This must be secured in order to reduce the risk of snagging the strap. In one known arrangement, this is done by using Velcro (RTM) to attach the free end of the strap to the portion of strap around the cylinder. Whilst this is satisfactory, the free end of the strap can become detached and loose, thereby introducing a potential hazard.

p-0004It is therefore desirable to provide an arrangement in which the free end of the cylinder-retaining strap is more securely retained.

p-0005According to one aspect of the present invention there is provided a gas-cylinder retaining assembly for retaining a gas-cylinder on a harness for breathing apparatus, comprising: a strap arranged in use to be coupled to the harness and a retaining portion of which is arranged to pass around at least a portion of the cylinder; a tensioning device arranged for tightening the retaining portion of the strap around the cylinder such that the cylinder is held to the harness, and wherein a free portion of the strap, having a free end, extends from the tensioning device; and a retaining buckle arranged for retaining the free portion of the strap, the retaining buckle comprising: a positioning slot through which in use the retaining portion of the strap passes; a pivot member which in use is located between the cylinder and the retaining portion of the strap; and a retaining slot arranged in use to receive the free end of the strap; wherein in use the retaining buckle is pivotable between at least a loading position in which the free end of the strap can be inserted into the retaining slot, and a retaining position in which at least part of the free portion of the strap is held between the retaining buckle and the retaining portion of the strap.

p-0006In one embodiment the pivot member of the buckle defines a side of the positioning slot. Preferably the positioning slot and the retaining slot are separate, preferably parallel, and preferably laterally spaced from one another.

p-0007In a preferred arrangement the pivot member is shaped such that the force acting on the pivot member due to the tension in the retaining portion of the strap causes the retaining buckle to be held in the retaining position.

p-0008In a preferred arrangement the tension in the retaining portion of the strap is increased when the retaining buckle is moved from the retaining position to the locating position.

p-0009The shape of the pivot member may be substantially that of a rectangular prism. At least a portion of the retaining buckle may be textured so as to grip the strap. The retaining buckle may be curved so as to follow the surface contour of the gas-cylinder when the buckle is in the retaining position. The retaining buckle may be made from plastics material.

p-0010According to a further aspect of the present invention there is provided a harness for breathing apparatus comprising a gas-cylinder retaining assembly according to any statement herein.

p-0011The invention may comprise any combination of the features and/or limitations referred to herein, except combinations of such features as are mutually exclusive.

p-0012Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

p-0013<figref idrefs="DRAWINGS">FIG. 1</figref> schematically shows a harness for breathing apparatus having a gas-cylinder retaining assembly according to an embodiment of the present invention;

p-0014<figref idrefs="DRAWINGS">FIG. 2</figref> schematically shows the harness of <figref idrefs="DRAWINGS">FIG. 1</figref> with a gas cylinder attached thereto;

p-0015<figref idrefs="DRAWINGS">FIG. 3</figref> shows schematically the cross-section A-A of <figref idrefs="DRAWINGS">FIG. 2</figref>;

p-0016<figref idrefs="DRAWINGS">FIG. 4</figref> schematically shows the retaining buckle of the gas-cylinder retaining assembly shown in <figref idrefs="DRAWINGS">FIG. 1</figref>;

p-0017<figref idrefs="DRAWINGS">FIG. 5</figref> schematically shows the retaining buckle of <figref idrefs="DRAWINGS">FIG. 4</figref> in use in a loading position;

p-0018<figref idrefs="DRAWINGS">FIG. 6</figref> schematically shows the retaining buckle of <figref idrefs="DRAWINGS">FIG. 4</figref> in use in a retaining position;

p-0019<figref idrefs="DRAWINGS">FIG. 7</figref> schematically shows an enlarged view of the retaining buckle of <figref idrefs="DRAWINGS">FIG. 4</figref> in a loading position; and

p-0020<figref idrefs="DRAWINGS">FIG. 8</figref> schematically shows an enlarged view of the retaining buckle of <figref idrefs="DRAWINGS">FIG. 4</figref> in a retaining position.

p-0021<figref idrefs="DRAWINGS">FIG. 1</figref> shows a harness <b>100</b> for breathing apparatus comprising a back frame <b>102</b> (otherwise known as a back plate), two shoulder straps <b>104</b>, <b>106</b>, a waist strap <b>108</b>, a reducer valve <b>110</b> and a cylinder retaining assembly <b>10</b>. With reference to <figref idrefs="DRAWINGS">FIG. 2</figref>, in use, the gas cylinder valve <b>2</b> is attached to the reducer <b>110</b> and a gas cylinder <b>1</b> is secured against the back frame <b>102</b> using the cylinder retaining assembly <b>10</b>.

p-0022As shown in <figref idrefs="DRAWINGS">FIG. 3</figref>, the gas cylinder retaining assembly <b>10</b> comprises a strap <b>20</b>, a tensioning device <b>30</b> and a retaining buckle <b>40</b>. The strap <b>20</b> is a continuous length of material that is attached to the tensioning device <b>30</b> at a first end <b>22</b> and has a second free end <b>24</b>. The free end <b>24</b> is folded and stitched to prevent fraying of the strap. The strap <b>20</b> is attached to the back frame <b>102</b> of the harness <b>100</b> by passing the free end <b>24</b> through a first slot <b>101</b> at a first side of the back frame <b>102</b> and then through a second slot <b>103</b> at a second side of the back frame. The free end <b>24</b> of the strap <b>20</b> is then fed through a positioning slot <b>42</b> of the retaining buckle <b>40</b>.

p-0023<figref idrefs="DRAWINGS">FIG. 4</figref> shows a detailed view of the retaining buckle <b>40</b>. The retaining buckle <b>40</b> comprises a positioning slot <b>42</b>, a pivot member <b>44</b> and a retaining slot <b>46</b>. The positioning slot <b>42</b> and retaining slot <b>46</b> are laterally spaced from one another and are parallel. The pivot member <b>44</b> defines a side of the positioning slot <b>42</b>. The retaining buckle <b>40</b> also comprises a tongue portion <b>48</b>. The retaining buckle <b>40</b> is slightly curved along its length so that it conforms to the surface contour of the cylinder when it is in a retaining position (described in detail below).

p-0024The free end <b>24</b> of the strap <b>20</b> is then fed through three slots <b>32</b>, <b>34</b>, <b>36</b> in the tensioning device <b>30</b>. The free end <b>24</b> of the strap <b>20</b> is pulled tightly through the tensioning device <b>30</b> so as to tension a retaining portion of strap <b>26</b> around the gas cylinder <b>1</b>. This holds the cylinder <b>1</b> tightly against the back frame <b>102</b>. A free, non-tensioned portion of strap <b>28</b> extends from the tensioning device <b>30</b>. The retaining buckle <b>40</b> is then used to secure the free portion <b>28</b> of strap <b>20</b>.

p-0025The retaining buckle <b>40</b> is slid along the tensioned retaining portion of the strap <b>26</b> until it is in the proximity of the free end <b>24</b> of the strap <b>20</b>. As shown in <figref idrefs="DRAWINGS">FIG. 5</figref>, the retaining buckle <b>40</b> is moved to a loading position in which it is approximately perpendicular to the cylinder. This is done by lifting the tongue <b>48</b> of the retaining buckle <b>40</b> which causes the retaining buckle <b>40</b> to pivot about the pivot member <b>44</b>. The free end <b>24</b> of the strap <b>20</b> is then inserted into the retaining slot <b>46</b> of the retaining buckle. As shown in <figref idrefs="DRAWINGS">FIG. 6</figref>, the retaining buckle <b>40</b> is then moved to a retaining position by pushing down on the tongue <b>48</b> causing the retaining buckle <b>40</b> to pivot about the pivot member <b>44</b>. A part of the free portion <b>24</b> of the strap <b>20</b> is now held between the underside of the tongue <b>48</b> and the tensioned retaining portion of the strap <b>26</b>. This securely holds the free portion of the strap <b>24</b> in place.

p-0026The operation of the retaining buckle <b>40</b> will now be explained in more detail with reference to <figref idrefs="DRAWINGS">FIGS. 7 and 8</figref>. As can be seen, in use the pivot member <b>44</b> of the retaining buckle <b>40</b> is located between the gas-cylinder <b>1</b> and the tensioned retaining portion <b>26</b> of the strap <b>20</b>. The tensioned portion <b>26</b> of the strap therefore exerts a force on the pivot member <b>44</b> in a direction towards the cylinder. The pivot member <b>44</b> is substantially a rectangular prism and has first and third opposing sides <b>44</b><i>a</i>, <b>44</b><i>c </i>that are wider than second and fourth opposing sides <b>44</b><i>b</i>, <b>44</b><i>c</i>. When the retaining buckle <b>40</b> is in the loading position (<figref idrefs="DRAWINGS">FIG. 7</figref>) the second side <b>44</b><i>b </i>of the pivot member <b>44</b> is in contact with the tensioned portion <b>26</b> of the strap <b>20</b> and the fourth side <b>44</b><i>d </i>of the pivot member <b>44</b> is in contact with the cylinder <b>1</b>. When the retaining buckle <b>40</b> is in the retaining position (<figref idrefs="DRAWINGS">FIG. 8</figref>) the first side <b>44</b><i>a </i>of the pivot member <b>44</b> is in contact with the tensioned portion <b>26</b> of the strap <b>20</b> and the third side <b>44</b><i>c </i>is adjacent the cylinder <b>1</b>.

p-0027When the retaining buckle <b>40</b> is moved from the retaining position to the loading position the tension within the tensioned portion <b>26</b> of the strap <b>20</b> is increased. This is because the first side <b>44</b><i>a </i>of the pivot member <b>44</b> is longer than the second side <b>44</b><i>b </i>of the pivot member <b>44</b>. Therefore, in order to move the retaining buckle <b>40</b> from the retaining position to the loading position a lifting force must be applied to the tongue <b>48</b> of the retaining buckle <b>40</b>. This ensures that the retaining buckle <b>40</b> does not move from the retaining position accidentally, thereby inadvertently releasing the free portion <b>28</b> of the strap.

p-0028When the retaining buckle <b>40</b> has been rotated by approximately 90°, the tensioned portion <b>26</b> of the strap <b>20</b> rests against the second side <b>44</b><i>b </i>of the pivot member <b>44</b> and the fourth side <b>44</b><i>d </i>of the pivot member <b>44</b> rests against the cylinder <b>1</b>. Since the fourth side <b>44</b><i>d </i>of the pivot member <b>44</b> fits against the cylinder <b>1</b>, the retaining buckle <b>40</b> is prevented from moving back to the retaining position. This allows the free end <b>24</b> of the free strap portion <b>28</b> to be inserted into the retaining slot <b>46</b>. To return the retaining buckle <b>40</b> to the retaining position, a small force is applied to the tongue <b>48</b> and the tension in the tensioned portion <b>26</b> of the strap <b>20</b> acting on the pivot member <b>44</b> returns the retaining buckle <b>40</b> to the retaining position. The retaining buckle <b>40</b> uses the tension within the tensioned retaining portion <b>26</b> of the strap <b>20</b> to provide a snap-type arrangement.