Choosing
shock absorber may not be easy. However if certain point is kept in mind
your work can be eased to a greater extent. It is the application that
determines the mounting methods of the shock absorber and the types of shock
absorber to be chosen.
Important factors that need to be considered before selecting shock
absorber are:
- Type of load to be stopped.
- Load weight and velocity.
- Potential shock to equipment, number of impacts per unit of time, and
ambient conditions.
There are different types of loads that are encountered by the shock
absorber. These loads include pure inertial, rotating, free-falling and
loads subject to an additional propelling force. Size depends on the load
weight and velocity.
Shock absorber is available with both internal and external accumulator.
Internal accumulator shock absorber is more preferred because it is filled
with oil and is ready for immediate use whereas external accumulator shock
absorber requires higher installation cost.
The cycle rate of the shock absorber should also be considered before
buying shock absorber. Shock absorber would fail if it handles too many
impacts within a given time. Too many impacts may result in poor
performance. The fluid will be heated if rapid cycling is done thereby
reducing the ability of shock absorber to dissipate energy.
Some other factors that effects the working of the shock absorber includes
extreme temperatures, load acceleration, propelling force applied to the
load, and time limitations imposed on the equipment.
The length of the stroke is inversely proportional to the amount of impact
the shock absorber can accommodate. If the stroke length is doubled, the
impact of the load can be reduced to half. Due to this it is recommended
that the size of the shock absorbers should be 50% to 60% of capacity.
Piston rod return is one of the important selection criteria for the shock
absorber. There are three ways by which the piston rod is actuated. These
ways include return spring, air or oil and mechanical units. In return
spring, the piston rod is brought to rest after being unloaded. In air or
oil system, mechanical device is used for the return of the piston.
