Figure 13-20.—No spin differential—exploded view. governed   by   the   speed   of   the   wheel   applying tractive effort. The no-spin differential does not contain pinion gears  and  side  gears  as  does  the  conventional differential.   Instead,   it   consists   basically   of   a spider attached to the differential drive ring gear through  four  trunnions.  It  also  has  two  driven clutch  members  with  side  teeth  that  are  indexed by  spring  pressure  with  side  teeth  in  the  spider. Two side members are splined to the  wheel  axles and,  in  turn,  are  splined  into  the  driven  clutch members. AXLES A  live  axle  is  one  that  supports  part  of  the weight   of   a   vehicle   and    drives    the    wheels connected to it. A dead axle is one that carries part of  the  weight  of  a  vehicle  but  does  not  drive  the wheels. The wheels rotate on the ends of the dead axle. Usually, the front axle  of  a  passenger  car  is  a dead axle and the rear axle is a live axle. In four- wheel drive vehicles, both front and rear axles are live  axles;  in  six-wheel  drive  vehicles,  all  three axles are live axles. The third axle, part of a bogie drive, is joined to the rearmost axle by a trunnion axle.  The  trunnion  axle  attaches  rigidly  to  the frame. Its purpose is to help distribute the load on the rear of the vehicle to the two live axles that it connects. Four types of live axles are used in automotive and   construction   equipment.   They   are:   plain, semifloating,    three-quarter    floating,    and    full floating. The  plain  live,  or  nonfloating,  rear  axle,  is seldom  used  in  equipment  today.  The  axle  shafts in  this  assembly  are  called  nonfloating  because they are supported directly in bearings located in the   center   and   ends   of   the   axle   housing.   In addition to turning the wheels, these shafts carry the entire load of the vehicle on their outer ends. Plain   axles   also   support   the   weight   of   the differential case. The semifloating axle (fig. 13-21) used on most passenger cars and light trucks has its differential case   independently   supported.   The   differential carrier relieves the axle shafts from the weight of the  differential  assembly  and  the  stresses  caused by its operation. For this reason the inner ends of the axle shafts are said to be floating. The wheels are  keyed  to  outer  ends  of  axle  shafts  and  the outer  bearings  are  between  the  shafts  and  the housing.  The  axle  shafts  therefore  must  take  the stresses caused by turning, skidding,  or  wobbling of the wheels. The axle shaft is a semifloating live axle that can be removed after the wheel has been pulled off. Figure 13-21.—Semifloating rear axle. 13-17