Belleville Washers

A conical type spring washer, the Belleville Washer is designed to maintain constant pressure on bolted aluminium electrical joints.
On high current, bolted joints, the aluminium terminal and the steel bolt expand and contract at different rates as a result of thermal cycling. Belleville washers, with their large loads and deflections, add a high degree of flexibility to the bolt. This virtually eliminates the loss of clamping force and results in a cool, stable joint.

• Select the largest compression washer possible. There should be no interference with washers on adjoining bolts or overhang at the edge of the connector.
• Fit compression washers under both bolt head and nut, convex side out as shown at right.
• Tighten the nut until a sudden increase in torque is noticed. The compression washer is now flattened. It is not necessary to "back off" the nut after tightening.
• Bolts and nuts should be steel, mechanical zinc-plated. There should be no thread interference between the bolt and the nut. It is recommended that the thread is lubricated with grease.

Transition Plate: Aluminium/Copper

Manufactured by fusion welding thin aluminium and copper sheets back to back, Electropar's tin plated transition plate is designed for making the transition between aluminium and copper.
Two millimetres thick, Electropar's tin plated transition plate is sized at 100mm x 100mm as standard so that it can be used for 4 hole palm connections. Transition plate can be cut and drilled to suit any smaller palm size.
When used as part of a bolted connection, all of the contact surfaces should be coated with EP Joint seal or Uniseal. Belleville washers should always be used to ensure constant joint pressure.