coil spring compressor is a tool that is used to safely compress
a spring for removal or installation on a vehicle. For example,
when servicing the suspension system of a car with coil springs,
a coil spring compressor squeezes the spring coils to reduce their
height. This gives enough room to slide the spring out of the control
arm. It also prevents the spring from shooting out when the lower
ball joint is disconnected.
Coil spring compressors may be screw-, ratchet-, or hydraulically-driven,
and may come with yokes that prevent slippage and damage to springs.
They differ in the maximum compressional force they can exert (known
as the maximum jaw loading) and the size of springs they can accomodate.