A welding device for joining components by resistance welding includes a pair of electrodes which can introduce an electrode force and an electrical welding current I.sub.S1 into the components, at least one further pair of electrodes which can introduce an electrode force and a further electrical welding current I.sub.S2 into the components, a power source which can generate the electrode forces, a coupling link which is mechanically connected between the power source and the pairs of electrodes and which can divide a total electrode force that can be generated by the power source into the electrode force and the further electrode force.

A spot welding system 10 includes a spot welding gun having an opposite electrode 44, a movable electrode 48, and a drive part 52, a position detection part 54 that detects a position of the movable electrode 48, and a pressure change calculation part that calculates an amount of change between first pressurizing force at a first attitude and second pressurizing force at a second attitude based on a first position of the movable electrode 48 when the drive part 52 has been driven by a first pressurizing force command at the first attitude, a second position of the movable electrode 48 when the drive part 52 has been driven by the first pressurizing force command at the second attitude, and the first pressurizing force command. The first pressurizing force command and the first pressurizing force coincide with each other.

An apparatus includes a housing, a lever, a plurality of gears and a sensor. The housing may be configured to receive a weld head. The lever may be rotatably attached to the housing and configured to convert a linear position of a free end of the lever relative to the housing into a first angular position of a first shaft relative to the housing. The gears may be configured to transform the first angular position of the first shaft to a second angular position of a second shaft. The sensor may be coupled to the second shaft and configured to generate a value representative of the linear position of the free end of the lever by a measurement of the second angular position of the second shaft.

A welding electrode unit may include a repositioning device that is movable. The repositioning device may include a stored-energy means by way of which a welding electrode connected directly or indirectly with the stored-energy means can have a force applied to it for the purpose of a repositioning movement. The repositioning device can be moved into a welding position by way of a forward movement and can be locked in the welding position.

A welding device may include a weld head. A welding device may include a positive welding electrode connected to the weld head. A welding device may include a positive electromagnetic actuator connected to the positive welding electrode. A welding device may include a positive position sensor configured to detect a position of the positive welding electrode. A welding device may include a positive force sensor configured to detect a force applied by the positive welding electrode. A welding device may include a negative welding electrode connected to the weld head. A welding device may include a negative electromagnetic actuator connected to the negative welding electrode. A welding device may include a negative position sensor configured to detect a position of the negative welding electrode. A welding device may include a negative force sensor configured to detect a force applied by the negative welding electrode.