Ball joint and rubber block

Spherical plain bearings, silent blocks and rubber blocks absorb movement and forces in components such as torque rods, anti-roll bars, spring mountings and chassis connections. A spherical plain bearing allows angular movement through a spherical sliding surface; a rubber block dampens vibrations as its elastomer deforms under load. Both may be used in the same position on a vehicle, but they are not interchangeable: the permitted angular movement, radial and axial loads, and stiffness must suit the design.

On a MAN TGL, TGM, TGS or TGX, a Mercedes Atego, Arocs or Actros, and buses such as the Lion’s City, Lion’s Coach, Citaro, Tourismo and Neoplan Cityliner, Tourliner and Skyliner, these parts vary according to axle configuration, suspension and permitted axle load. Different chassis and axle versions may exist even within a single series; this also applies to vans such as the MAN TGE and Mercedes Sprinter and Vito. Always identify parts using the chassis number, then check the installation position and part numbers. A visual comparison or selection based solely on the model name is never sufficient.

1. Spherical plain bearing for torque rods: allows the rod to accommodate angular movement while locating the axle.

2. Spherical plain bearing for anti-roll bar connections: allows movement between the anti-roll bar and the suspension.

3. Spherical plain bearing for spring mountings: accommodates angular movement at the relevant spring connection.

4. Spherical plain bearing for vibration damping: a version with elastomer dampens vibrations while allowing angular movement at the connection.

5. Spherical plain bearing to prevent galvanic corrosion: a version with an electrically insulating layer reduces the risk of galvanic corrosion between different metals.

1. Silent block for torque rods: dampens vibrations in the connection between the torque rod and the axle or chassis.

2. Silent block for anti-roll bar connections: dampens vibrations and limits movement at the anti-roll bar mounting.

3. Silent block for spring mountings: absorbs movement and vibrations at the spring mounting.

4. Silent block for vibration damping: dampens vibrations as the elastomer between the connected parts deforms.

5. Silent block to prevent galvanic corrosion: the insulating rubber layer limits direct contact between different metals, reducing the risk of galvanic corrosion.

1. Rubber block for axle bump stops: cushions contact when the suspension reaches its limit of travel.

2. Rubber block for chassis connections: dampens vibrations between connected chassis components.

3. Rubber block for anti-roll bar mountings: supports the anti-roll bar and dampens vibrations at the mounting.

4. Rubber block for vibration damping: dampens vibrations between the parts where it is fitted.

5. Rubber block to prevent galvanic corrosion: separates different metals and thereby reduces the risk of galvanic corrosion.

Typical symptoms include knocking when the load changes, unstable axle location, misalignment or uneven tyre wear. On rubber blocks, cracks, separation of the rubber-to-metal bond, deformation and contact between the inner and outer sleeves indicate wear. Spherical plain bearings may show play, corrosion, a damaged seal or a ball that moves stiffly. Bear in mind another potential issue: similar noises can also come from spring pins, mounting bolts or anti-roll bar connections. Do not replace a part based on noise alone.

Start with a visual inspection while the vehicle is safely supported. Then check the connection first with the axle at rest and again with the axle unloaded, as preload can mask play. Apply controlled force to the part with a pry bar and measure displacement between the inner sleeve and the mounting point with a dial indicator; compare the result with the vehicle specification and the opposite side. Check bolt holes for ovality and mountings for signs of movement. If necessary, remove a suspect spherical plain bearing to assess its resistance to movement, sliding surfaces and seal separately.

Before installation, check the bore, outer and inner diameters, installation width and whether the part has an eccentric design. The interference fit of a rubber block must meet the specifications for the housing; use a suitable press tool that applies force only to the specified metal ring. Observe the specified orientation of recesses or markings: this determines stiffness in the direction of load. For spherical plain bearings, the sliding-surface material and lubrication method are decisive. A maintenance-free version with a sliding liner must not automatically be treated as a lubricated bearing.

Clean the seat and replace damaged mounting components. Only fully tighten rubber-bonded connections at the specified ride height, so the elastomer is not permanently preloaded in its normal position. Use the specified tightening procedure and, after installation, check for free movement, secure mounting and, if necessary, axle alignment. This prevents a correctly selected part from failing prematurely due to installation errors.