L) The differential case is divided into two parts from the middle, and the tangent plane passes through the center line of each journal of the cross shaft, and each tangent plane has four seat holes at an interval of 90 degrees. The two parts are fastened together by bolts, and the driven gear of the main reducer is fixed on the flange of the left half of the differential case by rivets or bolts.
2) The four journals of the cross shaft are embedded in the corresponding seat holes of the differential case, and the side of the cross shaft is milled into a plane to contain lubricating oil.
3) Four conical planetary gears are respectively sleeved on the four journals of the cross shaft. In order to ensure lubrication, oil holes are drilled between gear teeth, and each planetary gear meshes with two straight conical half-shaft gears. The back of the planetary gear and the inner surface of the differential case at the corresponding position are made into spherical surfaces, and a low-carbon steel spherical washer is installed between them to reduce wear and ensure that the planetary gear and the half-shaft gear are aligned and correctly meshed.
4) The journal of the axle shaft gear is supported in the corresponding left and right seat holes of the differential case and connected with the axle shaft through splines. In order to reduce the wear of the gear and the housing, a mild steel flat gasket is installed between the axle gear and the differential housing.
Principle of differential: As shown in Figure 15, the differential housing 3 and the planetary gear shaft 5 are connected into a whole to form a planetary carrier. Because it is fixedly connected with the driven gear 6 of the main reducer, it is a driving part, and its angular velocity is set to ω0. ; The side gears 1 and 2 are driven members with angular velocities ω 1 and ω2. Point A and point B are the meshing points of the planetary gear 4 and two side gears respectively, the center point of the planetary gear is C, and the distances from point A, point B and point C to the rotating shaft of the differential are all R. ..
When the planetary gear only revolves around the rotation axis of the differential with the planetary carrier, it is obvious that the circumferential speeds of points A, B and C on the same radius are all equal (Figure 15b), and the value is ω0r. So ω0=ω 1=ω2, that is, the differential does not play a differential role, and the angular velocities of the two half shafts are equal to the angular velocities of the differential housing 3.
When the planetary gear rotates around its own axis 5 at angular velocity in addition to revolution, the circumferential speed of meshing point A is ω 1r = ω 0r+ω 4r4, and the circumferential speed of meshing point B is
ω2r=ω0r-ω4r4 .
So ω1r+ω 2r = (ω 0r+ω 4r)+(ω 0r-ω 4r).
That is ω 1+ω2=2ω0.
If the angular velocity is expressed in revolutions per minute, then
n 1+n2=2n0
This is the motion characteristic equation of a symmetrical bevel gear differential with two side gears with equal diameters. It shows that the sum of the rotational speeds of the left and right side gears is equal to twice the rotational speed of the differential housing, regardless of the rotational speed of the planetary gears. Therefore, in turning or other driving conditions, planetary gears can be used to rotate at corresponding speeds, so that the driving wheels on both sides can roll on the ground at different speeds without sliding.