Question

if you cant do it all solve the first page

Problem (4) F7/h8 PCD 60 25 82 H8 & Find dimension A and its tolerances. b- Fill the contents of the following table regarding the above shaft connection No. Part name No. off Material Specification (for standard parts) c. Write the type of fit between the following parts: Parts No. 1 & 2 Parts No.1 & 3 Parts No.1 & 5 Type of fit Fit designation

Answer 1

Hi first of all, this is a assembly drawing. The shaft tolerances to be derrived.

First we find out the nominal value of A.

A = 82- 12 - 25 - 12 - 24 = 9

Item 4 is a spacer, and the tolerance of spacer to be derived.

Given the total assembly length should be 82 H8

from the table given below H8 provides limits +0.054 / -0 mm

that means the value can vary at a range 82 to 82.054 mm

Now we have to define the tolerance flow direction.

Start Point F7/h8 30 PCD 60 Max is 11.95 since upper and lower is negative Max is 25.15 8.854 Max is 24.15 11.95+25.15 = 37.115 Max is 11.95 10 One side limit of value A = 44.954-24.15-11.95 = 8.854 82.054-37.1 = 44.954

Start Point F7/h8 30 PCD 60 Min is 11.90 since upper and lower is negative Min is 24.85 8.854 Min is 24.00 11.90+24.85 = 36.75 Min is 11.900 One side limit of value A = 45.304-24.00-11.90 = 9.404 82.054-36.75 = 45.304
From the above two pictures you can see that

Minimum value of A is 8.854 and maximum value of 9.404

otherwise 9.00 + 0.404/ -0.146

We can generalize this to 9.00 +0.4/ - 0.15

NOTE : the tolerance H8 is for holes , may not apply for linear dimension,For linear dimension ISO 2768 mK is applied , For 30 to 120 mm the tolerance will be +/- 0.15 mm

I have populated the table to the best of my knowledge.

See the bottom picture for key hole calculation.

No	Part Name	No off	Material	Specification ( standard parts)
1	Shaft	1	Steel EN 24 or SS	Dia 35 mm x 85 mm
2	Nut with flange	1	Steel	M 20 x 1.5
3	Gear	1	Steel	Hubless gear with Key hole PCD 60 No. of teeth = 60 Module = 1 Hole dia 20mm Key hole width = 6.00 -0.015/-0.051 Keyhole depth = 2.8   -0.015/-0.051
4	Spacer	1	Steel or Brass	L= 9.00 +0.4/-0.15 , ID 30 F7/h8, thickness 2mm
5	Bearing	2	Standard	ID 30mm x OD 37 - 45 mm x 12 mm eg SKF HK 3012
6	Key	1	Steel	Length 20 mm, Width 6mm height 6mm

SHAFT Keys and Keyways Shaft diameter d mm Shaft torque T Nm Key length L mm Solve Reset Print key width b mm key heighth mm keyway depth shaft t1 mm keyway depth hub t2 mm shear force Fs = T/(d/2) shear stress key T = Fs/(LT) 83.33 MPa bearing pressure p = Fs/(h/2) 166.67 MPa Nominal torsional stress T = T/(n/16/ 3), dk=d-tı 113.38 MPa Key dimensions: Parallel keys are most commonly used. The key and key seat cross section are ISO standardized. The key length should be less than about 1.5 times the shaft diameter to ensure a good load distribution over the entire key length when the shaft becomes twisted when loaded in torsion. 10 KN Stresses: Since compressive stresses do not cause fatigue failure, the bearing pressure is limited by the material yield strength YS of the weakest part, commonly the hub. The maximum shear stress in the key and the maximum torsional shear stress in the shaft can be derived from the yield strength of the shaft material.

c, This is tricky and depends on manufacturer.

Ideal fits are given below.

	Parts 1 & 2	Parts 1&3	Parts 1 and 5
Type of Fit	Threaded	Key lock	Bearing
Fit designation	Tight fit	Transition/ Tight	Press fit( transition to Tight )