This document defines limits, fits, and tolerances for mechanical parts. It defines limits as the maximum and minimum allowable sizes between which the actual size must fall. It describes three common fits - clearance fit, interference fit, and transition fit. Clearance fit always has a gap between parts, interference fit causes overlapping, and transition fit allows for both clearance and interference. Tolerances are defined as the total permissible variation between the maximum and minimum limits, which can be either unilateral with variation in one direction, or bilateral with variation in both directions.

1. Nilesh Zende(Patil) &Aniket Birajdar (Patil)
T.y. Mechanical

2. ◦ Defination:- The limit can be defind as, when two
extreme allowable sizes, between which the actual
size is contained are called limits.
◦ Limits are two extreme allowable sizes of a given
dimensions.
1.Maximum limit of size:-The greater of two is known as
maximum limit of size.
2.Minimum limit of size:-The smaller of two is known as
minimum limit of size.

4.  Defination:- degree of tightness between two
parts.
OR
relationship between two existing parts(i.e.shaft
and hole)

5. 1. Clearance Fit
2. Interference Fit
3. Transition Fit

6.  Always has a gap between two mating parts.
 Shaft size is small , compared to hole size.
 Generally in this type of fit, the lower limit size of
the hole is greater or at least equal to the upper
limit size of the shaft.
 Use:- pivots , latches fit of parts exposed to
corrosive effects etc.

8.  It is a fit where both clearance and interference
may occur in the coupling.
 Here tolerance zones of the hole and shaft are
partly or completely interface.
 Use:- Pulleys and bushing, Flushed bolts etc.

10.  It always overlap & are used mainly for press fits
where the two parts are pushed together, and
require no other fasteners.
 The upper limit size of the hole is smaller or at
least equal to the lower limit size of the shaft.
 Use:-In bearing bushings,flanges etc.

12.  Defination:-It can be defined as the total
permissible variation of size
OR
The difference between the maximum limit and
minimum limit

13. 1. Unilateral tolerance:-varition is permittedin an
direction only from the design size or zero line.
2. Bilateral tolerance:-variation is allowed in both
directions from the design size or zero line.

15. 1. www.engineering fitsandtolerance.com