Suspension Components

Air spring bellows, levelling valves, shock absorbers, leaf and parabolic springs, torque rods, stabiliser bushes, cab and engine mounts.

Features

A bellows that has run flat is replaced rather than re-inflated, because the lobe creases against the piston while deflated and the crease becomes the split.
Levelling valves set ride height, and a valve out of adjustment wears bellows and shock absorbers together.
Shock absorbers are replaced in axle pairs, since one new unit against one worn unit loads the axle unevenly.
Torque rod and V-stay bushes control axle geometry under drive and braking, and worn bushes show up as tyre scrub.
Cab mounts and engine mounts are inspected with suspension work, because their failure imitates a suspension fault.

Figure	Typical range	Unit	Why it matters
Component	air spring / shock absorber / leaf spring / torque rod / bush		Identifies the line.
Design height	250 - 400	mm	Ride height and travel for air springs.
Mounting arrangement	stud and bolt pattern from the removed part		Bolt-up compatibility.
Extended and compressed length	480 / 300	mm	Shock absorber travel.
Spring leaf count and thickness	3 leaves x 30	mm	Load rating for the axle.