《汽车理论》课程教学课件（英文讲稿）第7章 汽车的通过性 Passing Ability of Vehicle 7.2 Stepping Ability and Striding Ability（汽车越台跨沟能力）

7.2 Stepping Ability and Striding Ability（越台能力）1.SteppingAbility(1) 4X2 (rear drive)I)the case of only front wheel contact with stephw?Assumed T,, Fw T, could be ignored (constantlowspeed)HFx2 = F, = Fz20x2Z2MU

1. Stepping Ability （越台能力） （1）4×2 （rear drive) 1)the case of only front wheel contact with step——hw1 ? Assumed Tj , FW, Tf could be ignored （constant low speed) 1 1 2 2 0 f X X Z T F r F F F       7.2 Stepping Ability and Striding Ability

4x2rear drive1bfFz1aQhoD百师Fz cos α ++ fFz sin α-βFzz = 0Fz sin α + Fz2 - fFz cos α-G= 0DDfF=0+Fz,L-Ga-βF72Z122

L a b h0 D FZ 2 hw   G FZ1 Z1 fF FZ 2  4 2  rear drive 1 1 2 1 2 1 1 2 2 cos sin 0 sin cos 0 0 2 2 ZZZ Z Z Z Z Z Z F fF F F F fF G D D fF F L Ga F                 

ASubstitutionG、FzZ2DD+tsinα -DfDacOSα =2LL2L90.5D- hh1~0sinaαD0.5D

1 sin 2 1 1 cos 2 2 f a f Df L L f a D fD L L L                            ＋ 0.5 sin 1 2 0 0.5 D h h w w f D D       G F F Z Z 1 2 Substitution 、

7(告),=21-a/ L1-a/ L-(@D/2L)(告)一Step height per front wheel diameterL / D or α / L个→(h, / D),个

1 2 1 1 1 1 2 / 1 1 / ( / 2 ) diameter w w h D a L a L D L h D                                        ——Step height per front wheel 1 / / ( / ) w L D a L h D    or

2) In the case of only rear wheel contact with step-hw2?Fx1=0LFr2 = Fo2 = Fz20baGFz29hoDDαfFz4x2rear driveFz1fFz + Fz2 cos α -βFzz sin α = OFzi +Fz2 sin α +Fzz cosα-G= 0DDOF=0-+ Fz,L-Gb- fFZ2L22

L D FZ1 G h0 FZ 2  FZ 2  Z1 fF D 4 2  rear drive a b 1 2 2 1 2 2 2 1 1 cos sin 0 sin cos 0 0 2 2 Z Z Z Z Z Z Z Z Z fF F F F F F G D D F F L Gb fF                   2）In the case of only rear wheel contact with step——hw2 ? 1 2 2 2 0 x x Z F F F F     

2hand f ~ 0sinα = 1D(分)-[(-)(台)is nothing to do with vehicle(告)≥(分)The stepping ability of reardrivefour-wheel vehicle is determined by thestepping ability of drive wheel.>Dis responsible forthe stepping abilityofthevehicle

2 2 2 2 sin 1 0 1 1 1 2 1 . w w w h f D h D h is nothing to do with vehicle D                             and  The stepping ability of rear drive four￾wheel vehicle is determined by the stepping ability of drive wheel. 1 2 w w h h D D              ＞ D is responsible for the stepping ability of the vehicle

(2)4X4(Jeep four-wheel drive)>Both front and rear drive wheels double the steppingLabilityofvehiclebapFziGQhhDMDFA下市Z2GhoDDFBPFα市市市TFZ1Z2

Both front and rear drive wheels double the stepping ability of vehicle. （2）4×4 (Jeep four-wheel drive) G L h0 D FZ2 hw   G FZ1 FZ1 FZ2 h0 FZ2 FZ 2 FZ1  D FZ1 a b 

D1+@acoS αL2L91D@D:0sin α2L2L0.5D-hh1中sinα =D0.5Da()个二LDD

2 1 1 cos 2 1 sin 0 2 2 a D L L D D L L                         ＋- 0.5 sin 1 2 0 0.5 D h h w w f D D       1 1 L a h h w w D D L D                

PD(cos β-@sinβ)+sinaα2Lcos β cosα +Dsin βcoS α2L2-0.5D-hsinα =0.5DaL个→(告1LD

2 2 0 (cos sin ) sin 2 1 cos cos 1 1 1 sin cos 0 2 2 D L a L h D D L L L                                                   0.5 sin 1 2 0 0.5 D h h w w f D D       2 2 w w L a h h D D L D                

hw / D0.50.4h14=0.18 ~ 0.260.3D0.20.14×2 rear drive00.10.20.30.50.4

0.18 ~ 0.26 w h D =  / W h D0 0.1 0.2 0.3 0.4 0.5 0.1 0.2 0.3 0.4 0.5 4 4  4 2 rear drive 