2.1 screw, bolt connection
2.1.1
When screws, bolts and nuts are fastened, they must not strike or use unsuitable rotary tools and plate hands. After fastening, the screws, nuts, screws and bolts must not be damaged.
2.1.2
For fasteners required to tighten torque, torque wrenches should be tightened according to the prescribed tightening torque. The tightening torque of the bolt which does not tighten torque may refer to the provisions of Appendix 1.
2.1.3
When the same part is fastened with multiple screws or bolts, the screws (bolts) need to be tightened clockwise, staggered and symmetrical. If there is a locating pin, it should start with screws or bolts near the locating pin.
2.1.4
When using a double nut, a thinner nut should be installed and a thick nut should be installed.
2.1.5
Screws, bolts and nuts are tightened, screws and bolts should generally expose the 1-2 nuts of the nut.
2.1.6
When screws, bolts and nuts are tightened, the supporting surface should be fitted to the fastened parts.

2.2 pin connections
2.2.1
The end pin should generally be slightly higher than the surface of parts with cone pin into the screw tail of related parts, the end should sink into the hole.
2.2.2
A cotter pin related parts, the tail should be 60 degrees 90 degrees.
2.2.3 important taper pin assembly should be painted with inspection hole, the contact length should not be less than 60% of the length of work, and should be distributed in the joints on both sides.
2.3 key connection
2.3.1
The two sides of the key slot of the flat bond and the fixed key should be evenly contact, and there must be no clearance between the matching surfaces.
2.3.2
When the key (or spline) fitted with a gap is assembled, the relative movement of the parts should not be unequal when the parts move along the axis.
2.2.3
The hook head key, takes the key assembly in its contact area should not be less than 70% of the area of work, and do not contact shall not be concentrated in one place; the exposed part of the length shall be the length of the 10%~15% slope.
2.4. Riveting
2.4.1
The riveted materials and specifications must conform to the design requirements.  The processing of rivet holes should be in accordance with the relevant standards.
2.4.2
The surface of the riveted parts shall not be damaged during riveting, and the surface deformation of the riveted parts shall not be made.
2.4.3
Except for special requirements, no loosening occurs after the general riveting, and the head of the rivet.
It must be in close contact with the riveted parts and should be smooth and round.
2.5 assembly of rolling bearing
2.5.1
The bearings must be cleaned before they are assembled.
2.5.2
For oil lubricated bearings, after assembly, approximately 1/2 cavities should be injected into the lubricating grease.
2.5.3
When assembling with the pressure entry method, the special pressure gear is applied or the rod or sleeve is padded on the interference ring, and the pressure or the strike force can not be passed through the roller and the cage.
2.5.4
The end face of the bearing inner ring should be close to the shaft shoulder. The cone roller bearing and the centripetal thrust bearing should not be more than 0.05mm, and the other bearings should not be more than 0.1mm.
2.5.5
After the bearing outer ring is assembled, the contact between the bearing cover of the positioning end and the gasket or the outer ring should be uniform.
2.5.6
Bearing assembly is removable, must be installed according to the inner and outer rings and alignment marks, not anti loaded or mixed with other bearing inner ring.
2.5.7
The bearing of the adjustable head assembly should be numbered at the end of the assembly in order to identify.
2.5.8
Bearing with eccentric sleeve, the tightening direction of the eccentric sleeve in assembly should be in accordance with the rotation direction of the shaft.
2.5.9
After the rolling bearing is loaded, the rotation of the relative motion parts should be flexible and portable, and there must be no stagnation. .
2.5.10
The axial clearance of single row tapered roller bearing, thrust angle contact bearing and bi-directional thrust ball bearing should meet the requirements of drawing and process.
The semicircle hole 2.5.11 bearing outer ring and open bearing seat and a bearing cover shall be paint with good contact, inspection method, and the bearing is in the range of 120 DEG symmetrical to the center line of the internal uniform contact; cover in symmetrical to the center line of 90 degree range of uniform contact with the bearing. In the range of 0.03mm with feeler check, not into the outer ring width 1/3.
2.5.12 on both sides of assembly shaft has a radial bearing radial clearance adjustable, and axial displacement in the two end caps limit, only one end bearing against the end cover, the other end must have the axial clearance of C= alpha Delta tl+0.15 (L: axis center distance (mm) alpha: axle material linear expansion coefficient of delta t: axis of maximum working temperature and ambient temperature difference (c) 0.15: axis after the remaining gap expansion (mm))