Slurry pumps typically have a volute casing which is rubber lined, as well as a rubber lined impeller in order to minimise wear to internal metal parts. As slurries can be highly abrasive, and travel at high velocity the rubber is used as a sacrificial liner. As the rubber wears, the tolerances within the unit become larger meaning the pump becomes less efficient. Designs have front and rear adjustment to reduce internal clearances to improve unit efficiency as they wear.