Selection of frame type
Common slewing ring classifies into four types: Single-row ball, two-row ball, cross-rolling pole, three-row pole
According to our experience and calculation, we have conclusion as follows:
Bearing capacity of single-row ball slewing is more than cross-row pole with same figure dimension.
Below 160 ton meters load of incline moment, adopts single-row ball slewing bearing can get higher quality & price rate than threw-row pole slewing bearing, that is principal selection. While when incline moment is longer than 160 tons meters, should consider three row pole slewing bearing.
2. Selection of single-row slewing bearing series
Domestically, at present single-row slewing bearing has specifications of 3 series: HS series and 01 series. New clients usually don't know how to choose, we think each series has its own adantage, we analyze as bellows:
Types and specifications of our Slewing Rings Types The Max. Dia. Of raceway  The Max. Dia.
Of Rolling Part  The max
Module of Gear
Singe row ball Slewing Rings  3550mm  60mm  24mm
Single-row Crossed Roller Slewing Rings  1700mm  45mm16mm
Dual Row Ball Slewing Rings  2800mm  50mm  24mm
Double-row Four-point slewing Rings  3550mm  50mm24mm
Tri-row Roller Slewing Rings  3550mm  50mm   24mm

Compare parameter of three series( take outer tooth with roll center diamter of 1250 as example)
Series  weight Kg  steel ball diameter mm  center diameter of roll path mm  roll path capacity N  Install bolt hole
QW1250*40  388  40  1250  3696800  32-26
011*35*1250  420  35  1250  3291100  40-26
HSW1250*40  490  40  1250  3696800  36-22

A. HS series single-row slewing bearing is the continue of the history. Before eighty of the last centenary, national main type is cross-roll pole, it was gradually instead by slewing bearing. In order to avoid mainframe's measurement being influenced, we design HS series single-row slewing bearing with outer figure same as former cross-row pole but inner construction changes to single-row type. It is characterized by large dimension, for example: Weight of HSN1250. 40 is 470Kg, while QNA 1250. 40 with same carrying capacity is 388Kg, so HS series cost more resource and the production cost of making HS series is 10% more than Q series with same carrying capacity, and also not as good as some products abroad.
Hence, to save cost and resource, should avoid use HS series. Considering change slewing bearing would change mainframe's relative measurement also, new design shouldn't use HS series anymore.

B. 01 series single-row slewing bearing is slewing bearing series which bases on axletree recommended by former Mechanical Ministry in 1984. Number of its install bolt hole are much, fair, but rolling path parameter resists unfair matching, take 011.45.1400 and 011.35.1400 slewing bearing as example, its outer dimension is as same as its installing dimension, and production cost is same too, but 011.45.1400 uses steel ball with diameter of 45mm, while 011.23.1400 uses stell ball with diameter of 35mm, hence the latter's carrying capacity reduces 22%. So when use 01 series single-row bearing, should select bigger steel ball.
C. Q series single-row slewing bearing is referenced on 01 series slewing bearing's parameter by Construction Ministry in 1986, its section size is more close with lighter weight and fine price & price rate.