Control relays for truck, commercial vehicle and tail lift – reliable switching in the on-board electrical system
Control relays are the compact switching components that convert smaller control signals into significantly higher load currents in the on-board system of trucks and commercial vehicles. They make it possible to cleanly decouple sensitive control units and operating elements from high switching and auxiliary currents, thus protecting sensitive electronics against overload. In this category you will find control relays for common commercial vehicle applications – including standard changeover relays, working current relays, flasher units, multi-function relays and control modules for use on truck and tail lift. At SULEJ Ladebordwand, decades of experience in maintenance and repair flow directly into the selection of these components – for reliable switching behaviour, defined reaction times and a long service life in daily operation.
Function and tasks on the commercial vehicle
A control relay connects a control circuit with a load circuit. An internal contact is closed or opened by means of an electromagnetic coil or an electronic switching circuit, thus supplying the downstream consumer with voltage. In the truck, control relays are used in many places: for lighting, glow plug system, fuel pump, fan, immobiliser and comfort functions. On the tail lift, control relays handle the targeted switching of auxiliary functions such as platform lighting, horn, warning lights or interlocks and work together with the control box and the power relays of the lift motor control system.
Designs, characteristic values and versions
Control relays are described by several characteristic values: coil voltage (typically 12 V or 24 V), switching capacity at the contact, contact type (NO, NC, changeover) and connection type (plug contacts, blade terminals, pin headers or soldered connections). Common are classic ISO mini-relays, micro relays for tight installation space and special high-current versions with reinforced contacts.
Multi-function relays combine several functions in one housing, such as time delay, flasher operation or load compensation for LED consumers. Control modules with integrated electronics also perform diagnostic tasks and report switching states back to higher-level control units. For use on commercial vehicles, protection class, vibration resistance and temperature range are decisive selection criteria. Robust housings made of impact-resistant plastic and encapsulated contacts protect the components from splash water, dust and road salt.
