The planetary gear hub of planetary gear output type planetary gear transmission system consists of six circumferential uniformly distributed transmission crankshaft holes and six circumferential uniformly distributed directly connected shaft holes. The distribution diameter of transmission crankshaft holes and directly connected shaft holes are 660 mm and 720 mm respectively. Under the condition of not changing the distribution diameter of 660 mm and 720 mm, the size of transmission crankshaft hole and direct connecting shaft hole should be reduced appropriately.

The diameter of transmission crankshaft is 110 mm. In the original design scheme, 23222cc / W33 self-aligning roller bearing is selected, and the outer diameter of bearing is 200 mm.

Available bearing models without changing the size of the drive crankshaft. Among them, the width of 24022cc / W33 bearing is too different from that of the original bearing, and the width of 24122cc / W33 bearing is suitable.

The rated load of the star gear reducer is 7.585 × 107 n · mm, the speed of the transmission crankshaft is 157.72 R / min, and the diameter of the transmission crankshaft hole is 660 mm.

Then the load of single bearing is:

Where: f-load of single bearing; T-rated load; d-diameter of distribution circle of transmission crankshaft hole.

By calculating the formula, the result shows that f = 38308.1 n.

The bearing of transmission crankshaft only bears radial load, and the axial load is close to 0. According to its main application, the working condition factor FD = 1.8 is selected. Therefore, the equivalent dynamic load is:

Where: P – equivalent dynamic load; FD – working condition coefficient; X – radial dynamic load coefficient; FR – radial load of bearing; Y – axial dynamic load coefficient; fa – axial load of bearing.

By solving the formula, P = 68 954.4 n.

According to the mechanical design manual, the basic dynamic load rating of 24122cc / W33 self-aligning roller bearing is 4.58 × 105N, and the life index is 10 / 3

Where: L10 – rated life of bearing; N – speed; Cr – Basic rated dynamic load of bearing; P – equivalent dynamic load of bearing; ε – life index.

The formula is: L10 = 58 206 H.

According to the size inspection and bearing life preliminary check, 24122cc / W33 self-aligning roller bearing meets the requirements. Therefore, in the aperture scheme, the author selects the transmission crankshaft aperture of 180 mm, the variation range is 10%.

The function of the straight shaft hole is to make the straight shaft connecting the left and right support plates pass through the planetary gear without contact with the planetary gear and no matching relationship; the initial size is 140 mm, and in the aperture scheme, the size of the straight shaft hole is selected to gradually reduce by 10%.