Abstract: The characteristic features of an experimental bit are related.The experimental bit is the main equipment used in studying the
forces to which the journal bearings of the tricone bit are subjected.
The experi-mental bit is designed according to the basic parameters of
XHP215ZY-3 type bit produced by the Chengdu Petroleum General Machinery-Building Plant of The Sichuan Petroleum Industry Administration.Through
experiments a set of curves are recorded.The radial and axial loads on
the big and small journal bearings of each cone are obtained，and the
load distribution percentages on the cones and bearings are calculated.
The result of data processing has proved the design of the experimental
bit to be successful and the recorded curves of load variations with time
to be reliable.Meantime, the experiments concerning the influence of
vertical relative positions of cones on their bearing loads are described.
At the end of this paper, several opinions on the present design of this
type of bit are put forward.