Choice Of Crane Rail Wheels

In order to choose a crane rail wheel, its diameter is determined by considering :

-the load on the wheel

-the quality of the metal from which it is made

-the type of rail on which it runs

-the speed of rotation of the wheel

-the group classification of the mechanism

4.2.4.1. Crane rail wheel size

To determine the size of a crane rail wheel, the following checks must be made :

-that it is capable of withstanding the maximum load to which it will be subjected, and

-that it will allow the appliance to perform its normal duty without abnormal wear.

The two requirements are checked by means of the following two formulae :

P_{mean III} ≤ P_L . C_1max . C_2max < 1,38 . P_L ≈ 1,4 P_L

Taking C_1max=1.2 and C_2max=1.15

and P_{mean I,II} / (b.D) ≤  P_L.C₁.C₂

(Note: For the meaning of the characters and the calculation method of each data（Such as "P_L""C₁""C₂"), please refer to the attachment 👇)

4.2.4.2. Notes

Note 1 :  The formulae apply only to wheels whose diameters do not exceed 1,25 m. For larger diameters experience shows that the permissible pressures between the rail and the wheel must be  lowered. The use of wheels of greater diameter is not recommended.

Note 2:  It should be noted that the limiting pressure PL is a notional pressure determined by supposing  that contact between the wheel and the rail takes place over a surface whose width is the useful width defined earlier (clause 4.2.4.1.2.) and whose length is the diameter of the wheel. The  method of calculating set out above is derived from application of the HERTZ formula, which may be written :

σ_cg² / ( 0,35 . E ) = P / ( b . D )

where:

σ_cg²  is the compressive stress in the wheel and the rail in N/mm²

E the modulus of elasticity of the metal in N/mm²

P the wheel load in N

b and D in mm, being as defined above (clause 4.2.4.1.).

Taking KL to represent the value σ²_cg/(0.35.E) which has the dimension of a pressure in N/mm2 , the relation may be written :

K_L=P/(b.D)

and characterizes the wheel pressure on the rail. The formula of clause 4.2.4.1. is obtained by putting :

K_L=P_L.c1.c2