referring to fig1 and 4 , a stair climbing machine 10 in accordance with the present invention is shown . the stair climbing machine 10 comprises a base frame 20 , a tilting seat 30 , a tilting seat adjuster 40 , a handrail 50 , a handrail adjuster 60 , a staircase 70 , and a tread board adjuster 80 . the base frame 20 is adapted to be positioned on a floor to provide a supporting effect . the tilting seat 30 has a rear end thereof pivotally connected to a rear end of the base frame 20 . the tilting seat adjuster 40 comprises a first motor 41 , a first screw rod 42 , and a first sleeve 43 . the first motor 41 is pivotally mounted at an opposing front end of the tilting seat 30 . the first screw rod 42 has a top end thereof connected to the first motor 41 . the first sleeve 43 is threaded onto the first screw rod 42 with a bottom end thereof affixed to the base frame 20 . thus , when the first motor 41 is started to rotate the first screw rod 42 clockwise or counter - clockwise , the first screw rod 42 causes the first motor 41 to move axially upward or downward along the first screw rod 42 , thereby turning the tilting seat 30 upward or downward relative to the base frame 20 . the handrail 50 has a rear end thereof pivotally connected to an opposing rear end of the base frame 20 for holding by user &# 39 ; s both hands . the handrail adjuster 60 comprises a second motor 61 , a second screw rod 62 , and a second sleeve 63 . the second motor 61 is pivotally connected to an opposing front end of the handrail 50 . the second screw rod 62 has a top end thereof connected to the second motor 61 . the second sleeve 63 is threaded onto the second screw rod 62 with a bottom end thereof pivotally connected to the front end of the tilting seat 30 . thus , as shown in fig3 and fig9 , when the second motor 61 is started to rotate the second screw rod 62 clockwise or counter - clockwise , the second screw rod 61 causes the second motor 61 to move axially upward or downward along the second screw rod 62 , thereby turning the handrail 50 upward or downward relative to the tilting seat 30 . the staircase 70 comprises two opposing front chain wheels 72 , two opposing rear chain wheels 73 , two chains 74 , and a plurality of tread boards 75 that are arranged in a front - rear parallel manner . the two front chain wheels 72 are mounted at the front end of the tilting seat 30 in opposing left and right positions with a front wheel axle 722 . the two rear chain wheels 73 are mounted at the rear end of the tilting seat 30 in opposing left and right positions with a rear wheel axle 732 . each chain 74 is mounted around one respective front chain wheel 72 and one respective rear chain wheel 73 at one same side , enabling the respective chain wheels 72 , 73 to be rotated synchronously . each tread board 75 is pivotally connected between the two chains 74 with a respective tread board axle 752 so that each tread board 75 can be carried by the chains 74 to cycle , and can also be biased up and down relative to the tilting seat 30 . the staircase 70 further comprises a tread board adjustment frame 76 ( see fig7 ). the tread board adjustment frame 76 comprises two opposing side plates 77 , and two support rods 78 connected between the two side plates 77 . each side plate 77 has an elongated slot 772 ( see fig2 ) located near a front end thereof for the passing of the front wheel axle 722 , and a rectangular hole 774 ( see fig1 ) located near an opposing rear end thereof for the passing of the rear wheel axle 732 . the elongated slot 772 is larger than the outer diameter of the front wheel axle 722 . the rectangular hole 774 is larger than the outer diameter of the rear wheel axle 732 . thus , when the side plates 77 are driven by an external force , they can be moved alternatively up and down relative to the tilting seat 30 . as shown in fig7 , each side plate 77 further has a guide groove 776 located at an inner wall thereof . each tread board 75 is coupled between the guide grooves 776 of the two side plates 77 by a guide rod 754 . the guide rod 754 has two opposite ends thereof respectively mounted with a guide roller 756 that is rotatably coupled to the guide groove 776 of one respective side plate 77 to enhance tread board moving stability , allowing the respective tread board 75 to be moved synchronously with the tread board adjustment frame 76 . referring to fig4 - 8 , the tread board adjuster 80 comprises a third motor 81 , a third screw rod 82 , a third sleeve 79 , and an interlocking seat 83 . the third motor 81 is mounted at the tilting seat 30 . the third screw rod 82 has a front end thereof connected to the third motor 81 . the third sleeve 79 is threaded onto the third screw rod 82 with a bottom end thereof affixed to the interlocking seat 83 . thus , when the third motor 81 is started to rotate the third screw rod 82 clockwise or counter - clockwise , the third sleeve 79 is caused by the third screw rod 82 to carry the interlocking seat 83 axially forwards or backwards along the third screw rod 82 . the tread board adjuster 80 further comprises two opposing linkages 84 . as illustrated in fig4 , fig6 and fig8 , each linkage 84 comprises a front sliding rail 85 , a rear sliding rail 86 , a front sliding seat 87 , a rear sliding seat 88 , a bracket 89 , an upper sliding rail 90 , a lower sliding rail 91 , an upper sliding seat 92 , a lower sliding seat 93 , a first link 94 , and a second link 95 . the front sliding rail 85 is affixed to the tilting seat 30 . the rear sliding rail 86 is affixed to the tilting seat 30 opposite to the front sliding rail 85 . the front sliding seat 87 and the rear sliding seat 88 are respectively mounted on the front sliding rail 85 and the rear sliding rail 86 . the bracket 89 comprises a first prop rod 892 , and two second prop rods 894 arranged in parallel . the first prop rod 892 has opposing front and rear ends thereof respectively connected to the front sliding seat 87 and the rear sliding seat 88 . the second prop rods 894 have respective opposing front and rear ends thereof respectively connected to respective outer walls of the side plates 77 of the tread board adjustment frame 76 and the first prop rod 892 . the upper sliding rail 90 is affixed to a bottom side of the first prop rod 892 of the bracket 89 between the front sliding rail 85 and the rear sliding rail 86 . the lower sliding rail 91 is affixed to the tilting seat 30 to face toward the upper sliding rail 90 . the upper sliding seat 92 and the lower sliding seat 93 are respectively mounted at the upper sliding rail 90 and the lower sliding rail 91 . further , the lower sliding seat 93 is connected to one end of the interlocking seat 83 ( see fig4 ). thus , the lower sliding seat 93 can be carried to move by the interlocking seat 83 . the first link 94 has opposing top and bottom ends thereof respectively pivotally connected to the first prop rod 892 of the bracket 89 and the lower sliding seat 93 . the second link 95 has opposing top and bottom ends thereof respectively pivotally connected to the upper sliding seat 92 and the tilting seat 30 . further , the first link 94 and the second link 95 are pivotally connected together in a crossed manner . based on the above - described structural composition , if the user wishes to adjust the climb gradient , start up the first motor 41 to rotate the first screw rod 42 , thereby biasing the tilting seat 30 relative to the base frame 20 . at this time , subject to angular position change of the tilting seat 30 , the climb gradient is relatively changed . after reached the desired angle , turn off the first motor 41 to keep the tilting seat 30 in the adjusted angular position , and the user can thus step on the tread boards 75 to perform stair - climbing exercises on the desired climb gradient . because the angular position of the tilting seat 30 can be changed relative to the base frame 20 , in order to let the user hold the handrail 50 with the two hands under the ergonomic posture during the process the user is stepping on the tread boards 75 , the second motor 61 can be started up to rotate the second screw rod 62 in biasing the handrail 50 relative to the tilting seat 30 to a suitable angular position . after the tilting seat 30 reaches the desired angular position , turn off the second motor 61 , keeping the handrail 50 in the optimal angular position suitable for holding by the user &# 39 ; s both hands . on the other hand , the tread boards 75 can be slightly tilted with the change of the tilting seat 30 in the incline angle . in order to let the tread boards 75 to be constantly maintained in horizontal for stepping by the user as the angle of the tilting seat 30 is changed , the third motor 81 can be started up to rotate the third screw rod 82 in moving the lower sliding seat 93 via the interlocking seat 83 . when the lower sliding seat 93 is moved , the first link 94 and the second link 95 are biased relative to each other to move the bracket 89 upwards . at this time , the bracket 89 moves the tread board adjustment frame 76 upwards relative to the tilting seat 30 subject to matching between the front sliding seat 87 and the front sliding rail 85 and matching between the rear sliding seat 88 and the rear sliding rail 86 . during movement of the tread board adjustment frame 76 , the slide plates 77 are forced to bias the tread boards 75 relative to the tilting seat 30 , enabling the tread boards 75 to be maintained in horizontal after change of the incline angle of the tilting seat 30 , and allowing the user to conduct a stepping exercise with less effort . in order to let the stair climbing machine 10 to be operated efficiently and conveniently , the tilting seat adjuster 40 , the handrail adjuster 60 and the tread board adjuster 80 can be controlled to work synchronously through an electronic control measure so that when changing the incline angle of the tilting seat 30 , the tread boards 75 or the handrail 50 can be relatively biased to the optimal angular position suitable for exercise . in conclusion , the stair climbing machine 10 of the invention uses the tilting seat adjuster 40 to adjust the incline angle of the tilting seat 30 and the tread board adjuster 80 to adjust the horizontal angle of the tread boards 75 , enabling the user to conduct stair - climbing exercises at different climb gradients accurately and comfortably . further , the stair climbing machine 10 uses the handrail adjuster 60 to adjust the incline angle of the handrail 50 , or employs an electronic control measure to actuate the tilting seat adjuster 40 , the tread board adjuster 80 and the handrail adjuster 60 synchronously , enabling the user to get good support in the operation , and achieving the objects of the present invention .
an incline angle adjustable stair climbing machine includes a base frame , a tilting seat pivotally mounted at the base frame , a tilting seat adjuster for adjusting an incline angle of the tilting seat relative to the base frame , a staircase mounted at the tilting seat and including a plurality of tread boards biasable relative to the tilting seat , and a tread board adjuster mounted at the tilting seat for adjusting a biasing angle of the tilting seat to maintain the plurality of tread boards constantly horizontal for enabling a user to conduct stair - climbing exercises at different climb gradients while maintaining good posture .