text: fig1 shows the inboard side of typical seat 10 and a seat belt restraining system 12 used in a modern automobile vehicle . the seat 10 includes a lower cushion 14 and a back cushion 16 . a seat belt strap 18 extends from a spring loaded spool 20 mounted in the b - pillar of the vehicle up through a shoulder guide 22 mounted on the b - pillar . the strap extends from the shoulder guide 22 to an inboard guide 24 and from the inboard guide 24 to a floor mounted anchor point 26 on the outboard side of the seat 10 . the spring - loaded spool 20 may include a pretensioning device to take up slack in the strap 18 in a crash event as is well known in the art . the inboard guide 24 is mounted on the end of a tongue 25 which engages an inboard buckle 28 . the inboard buckle 28 comprises a buckle mechanism 29 that is mounted on one end of an extension strap 30 , the opposite end of which is attached to an inboard anchor 32 on the floor of the vehicle . fig2 is a perspective view showing the lower frame 33 of a modern four - way seat and its attachment to the floor of a vehicle . four mounting pads 34 for the seat are attached to the floor of the vehicle . two parallel lower rails 36 running fore and aft are secured to the mounting pads 34 . two upper rails 38 are slidably mounted to the lower rails 36 and are interlocked with the lower rails to allow sliding motion in the fore and aft directions , but to prohibit up and down or rotary motion relative to the lower rails . the bottom of the seat frame is formed by two side members 40 , a front crossbeam 42 , and a rear cross beam 44 . a seat pan 45 , omitted for clarity in this view , but partially shown in fig3 and 6 , spans the width of the seat and is supported by the two side members 40 , and the two cross beams 42 , 44 . the seat pan 45 supports a seat cushion 46 as shown in fig3 and 6 . four pairs of folding links 48 are positioned one each at the four corners of the seat to permit the height of the seat to be adjusted relative to the upper rails . the pairs of folding links each comprise a fixed link 49 that is attached to the upper rail 38 and a lifting link 50 that is pivoted at one end to the fixed link 49 and at the other end to one of the side members 40 . a suitable mechanism is used to raise and lower the seat as well known in the art . an inboard bracket 51 is attached to the upper rail 38 , and moves fore and aft with the seat . the inboard bracket 51 does not move up and down with the seat . an inboard buckle is normally attached to a mounting aperture 52 on the inboard bracket 51 . the upper and lower rails , the frame members for the seat , the lifting levers and the inboard bracket are all fabricated from steel , aluminum , or other metal alloy , as is the common practice in the art . fig3 shows the inboard side of a seat 54 with a variable buckle guide 56 attached to the upper rail 38 . the extension strap 30 of the inboard buckle 28 is attached to the side member of the seat through the variable buckle guide 56 as more fully explained below . the extension strap 30 may be made from metal , or seat belt strap material that is stiffened with a plastic or fiber covering so that the buckle will be extended from the seat toward the occupant . since the inboard buckle 28 is attached to the seat , the inboard buckle 28 moves fore and aft , and up and down with the seat . the typical length of an inboard buckle that is attached to and moves with the seat is between 150 and 200 mm . this positions the buckle mechanism 29 at about the midpoint of the occupant &# 39 ; s hips for maximum occupant protection in a crash event for all positions of the seat . attaching the inboard buckle to the seat allows the occupant to comfortably and easily locate the buckle mechanism 29 and clinch the tongue portion 25 of the buckle into the buckle mechanism 29 , regardless of the position of the seat . the variable buckle guide 56 preferably is bolted , welded or otherwise attached to the upper rail 38 and moves fore and aft with the upper rail and with the seat that is attached thereto . the variable buckle guide 56 does not move up and down with the seat when the height of the seat is adjusted by the occupant . fig4 and 5 show the variable buckle guide 56 and the components used to attach the inboard buckle 28 to the seat . the variable buckle guide 56 comprises a base plate 58 and an upright guide plate 60 with an elongated arcuate slot 62 . a lower convex portion 64 of the arcuate slot 62 is formed with serrations or teeth 66 . the teeth 66 formed in the arcuate slot 62 comprise a first set of teeth . an upper concave side 68 of the arcuate slot is smooth . an elongated plate or bug gear 70 fits inside of the arcuate slot 62 and has serrations or teeth 72 formed along the side of the gear that is opposite the teeth 66 formed in the slot . the teeth 72 formed on the bug gear 70 comprise a second set of teeth . the opposite side 74 of the bug gear is smooth . the dimensions of the bug gear 70 are such that it is able to slide in the arcuate slot 62 with the smooth side 74 of the bug gear in contact with the smooth side 68 of the arcuate slot without the teeth 72 of the bug gear coming into contact with the teeth 66 of the slot . the bug gear is formed with a mounting aperture 78 . a fastener such as a mounting post 76 is used to attach the inboard buckle 28 to the seat . one end of the mounting post 76 is welded or otherwise securely attached to the side member 40 of the seat . the mounting post extends through the arcuate slot 62 in the variable buckle guide 56 . the bug gear 70 is attached to the mounting post 76 by welding or an interference fit , and is positioned in the arcuate slot 62 . a load washer 80 and the extension strap 30 are mounted on the mounting post 76 so that the load washer is between the upright guide plate 60 of the variable buckle guide and the extension strap 30 . a mounting aperture 82 is formed in the end of the extension strap 30 to receive the mounting post 76 . the load washer 80 distributes forces from the extension strap 30 to a large area on the upright guide plate 60 , and helps to prevent inward motion of the extension strap toward the seat or the occupant in a crash event . a small washer 84 and a mechanical fastener 86 such as a pin or a circular clip are used to retain the extension strap 30 and the load washer 80 on the mounting post 76 . the variable buckle guide 56 , the mounting post 76 , the bug gear 70 and the load washer 80 may be fabricated from steel or aluminum or other metal or metal alloy having sufficient strength and wear characteristics to withstand the loads to which they will be subjected . fig6 is a side view of the seat 54 showing the arcuate path taken by the seat as the height of the seat is adjusted up or down using the lifting links 50 . the arcuate slot 62 in the variable buckle guide 56 is the same shape as the path taken by the seat 54 and shown by the arrows 88 as it is adjusted up and down to allow the mounting post 76 and the bug gear 70 to move freely in the arcuate slot 62 . fig7 is a detail view of the variable buckle guide 56 and the bug gear 70 showing the motion of the bug gear along the arrow 90 as the height of the seat is adjusted up and down . the smooth side 74 of the bug gear 70 slides along the smooth concave surface 68 of the arcuate slot 62 , and there is sufficient clearance between the teeth 72 of the bug gear and the teeth 66 of the slot that the teeth do not come into contact with one another . fig8 shows the motion of the bug gear 70 in a crash event . the forces in a crash event bend the mounting post 76 causing the bug gear to skew relative to the arcuate slot 62 , bringing the uppermost teeth 72 on the bug gear into contact with the teeth 66 of the arcuate . the lower smooth surface 74 of the bug gear comes into in contact with the smooth concave side 68 of the slot 62 . this position of the bug gear 70 causes it to bind in the slot 62 and transfers the load on the inboard buckle 28 to the variable buckle guide 56 which is attached to the upper rail 38 . thus , the load on the inboard buckle 28 is transferred to the upper rail 38 , and is diverted from the side member 40 of the seat . as a result , the seat and the folding links 48 do not receive the occupant load , do not distort , and do not create slack in the seat belt system , allowing the seat belt system to protect the occupant as intended . in operation , the seat and the seat belt are able to be used in the normal way . the seat 54 will move fore and aft , and up and down as required by the occupant . when moving the seat fore and aft , there is no motion of the bug gear 70 in the arcuate slot 62 since the variable buckle guide 56 is attached to the upper rail 38 and moves with the seat . when moving the seat up and down , the bug gear 70 will change position in the arcuate slot 62 as the mounting post 76 moves with the seat without the teeth 72 of the gear engaging the teeth 66 of the slot . the inboard buckle 28 will move with the seat since it is attached to the side member 40 of the seat , and therefore the inboard buckle mechanism 29 maintains a constant position relative to the seat , and will remain convenient to the occupant . since the inboard buckle moves with the seat , it can be short , between 150 and 200 mm in length , and it remains close to the occupant &# 39 ; s body . in a crash event , occupant loads are transferred from the belt 18 to the inboard buckle 28 and to the mounting post 76 . the force on the inboard buckle 28 is distributed over the upright guide plate 60 of the variable buckle guide by the load washer 80 . the upright guide plate 60 helps to prevent inward motion of the inboard buckle 28 toward the occupant , a potential source of slack in the seat belt 18 . the forces on the bug gear 70 causes it to rotate in the arcuate slot 62 , and causes the upper teeth 72 on the bug gear to lock with the teeth 66 in the arcuate slot . this transfers the load from the inboard buckle 28 to the variable buckle guide 56 , and to the upper track 38 to which the variable buckle guide 56 is attached . as a result , the load from the inboard buckle 28 is not transferred to the side member 40 of the seat , preventing local deformation of the side member and the folding links 48 . this maintains the tightness of the seat belt 18 around the occupant , minimizing injury to the occupant . having thus described a presently preferred implementation of the invention , various modifications and alterations will occur to those skilled in the art . for example , while the base portion of the variable buckle guide is shown in the illustrated embodiment as being generally perpendicular to the upright portion , arrangements can be used . the base and upright portion may be generally in - line , or at any desired angle relative to each other . still other modifications and embodiments will be apparent from this disclosure . the scope of the invention is defined by the appended claims .