Unlike an emergency stop switch, a main switch disconnects the entire power supply of a machine. It is necessary to ensure that a machine is free of voltage and that any repair or maintenance work can be carried out safely. The main switch must be protected against accidental switching on while the repairs or maintenance is being carried out. In most cases it can be secured by a padlock.
Special care should be taken if capacitors, coils or other components capable of storing electrical energy are used in the control system. These components have stored electrical energy even after the power supply has been disconnected and can therefore lead to accidents. Any repair and maintenance work should therefore only be carried out by a qualified technician and the warnings in the operating instructions should be observed.
In the case of substance-to-substance bonds, the force is transmitted through an atomic or molecular connection between the elements to be connected.
The best known examples of this type of connection are soldering, welding, gluing and vulcanising.
Modular sourcing is one of the most widespread procurement strategies in manufacturing based on the division of labour. Instead of individual parts, finished assemblies or modules that can be integrated in the final product without modifications are purchased.
For a company to concentrate more strongly on its own core competencies, a large part of the added value is generated outside the company. For this reason, modular procurement is also the most frequently used strategy. For example, at most automobile manufacturers, car seats are delivered as finished modules and only assembled as part of in-house production.
Modular procurement has not (yet) become established in the lift table industry. Most manufacturers have a very deep value chain, i.e. the lift table manufacturers carry out all the steps from the steel construction to the assembly of the lift table on site themselves. The only exception is often the hydraulic power units, which many manufacturers purchase and install as a ready-to-use module. Of course, there are also a few lift table manufacturers who have outsourced their steel construction or control engineering.
The motor contactor is nothing more than a switch that disconnects or establishes the power supply of an electric motor.
Just like relays, contactors disconnect the control and power circuits. Small coils are installed in the contactors for this purpose. These operating coils can be energised by the control circuit. The magnetic field created by the current switches the contacts of the component.
The motor protection protects an electric motor against mechanical and/or thermal overload.
A three-phase electric motor is usually protected by a motor protection switch or by an overload relay. While the motor protection switch directly interrupts the voltage supply to the motor, the relay is usually used to actuate a contactor, which disconnects the voltage supply. In both designs, the currents in the supply line are monitored thermally-mechanically, thermally-electronically or purely electronically through current measurement.
The voltage supply of the motor is disconnected in case of imminent overheating of the windings. The tripping speed depends on the current in the supply lines, i.e. at a higher current the circuit breaker trips faster. When designing the protective device, it is therefore important to pay attention to an appropriate reaction speed. The overload protection must trip before the insulation of the windings can be damaged.
Mounting bolts from simple round steel bars are mostly used for scissor lift tables. The platform sets down on these pins in the lowered position. This relieves the load on the scissors in the most unfavourable position for them.
Some lift table manufacturers fit rubber adapters over the mounting bolts to reduce noise emission when the lift sets down on them.