In order for the elevator car to start moving, the mechanical safety gear, the governor that engages it, and the system that tensions the governor rope must be operational. (This requirement must also be applied during installation for safety reasons, and no movement should be given to the suspension before the safety gear and governor are installed).

For the mechanical braking system (the safety gear) to function properly, both the overspeed governor and the rope tensioning system must be operational. This is why the mechanical brake, and the governor assembly are among the most critical components in elevator safety. In order for the governor to activate the brake, it must exert a minimum rope tension of 300N.

If the grooves of the governor sheave provide the correct groove angle and the casting quality of the governor ensures adequate hardness, the friction coefficient between the rope and the governor sheave (e^fα) will typically be between 2.5 and 3. During braking in the downward direction, a friction coefficient between 2.5 and 3 will develop between the governor rope and the grooves of the governor sheave. Therefore, a rope tension of 15 kg at the lower end will be sufficient. To achieve 15 kg of rope tension in both directions, the tensioning pulley must generate a tensile force of 30 kg on its shaft.

A relatively small weight on the governor tensioning pulley is usually sufficient. However, in the case of braking in the upward direction, the entire force required to pull the mechanical safety gear downwards with 300 N falls on the governor tensioning pulley. This corresponds to a tensile force of 600 N on the pulley shaft, which means the tensioning weight must be approximately 62 kg to achieve the required force.

 Compared to the initial case, twice the weight is required. When braking in the upward direction is ensured by the governor and the mechanical safety gear, the governor tensioning weights must be designed to meet this requirement. The same applies to governor tensioning springs. If a spring is used instead of a weight, it must still exert a force of at least 300 N at the moment the governor tensioning pulley opens the tension switch, even if the rope has stretched.

Otherwise, a slightly tensioned spring may mislead maintenance personnel and lead to highly risky situations. A spring mechanism that has largely lost its tensioning ability due to slight rope elongation may still make the rope appear tight, while in reality it applies too little force to engage the safety gear, essentially the same as having no mechanical brake at all. It is essential to ensure that the governor and its tensioning system always provide the required pulling force. A spring-type governor tensioner that meets standard conditions must still apply at least 300 N to the mechanical brake, even when the tension switch is triggered. These springs should not stretch more than 30%, as overstretching can prevent them from maintaining the required tension.

If the mechanical brake, governor, and tensioning system are not fully engaged and working together, the elevator must not be allowed to operate. For this reason, certain contacts in the elevator system, such as stop switches and the governor tension switch, must never be bypassed. Other safety contacts can be temporarily bypassed in specific situations, for example during electrical emergency rescue operations or leveling commands while the doors are open. The governor tension switch is required to operate reliably under mechanical force and remain active at all times. For this reason, using locked-type switches in the tensioning system can create serious risks. If the locking mechanism of the contact fails, which is a common issue with some switch models, it leads to a situation that does not align with the elevator’s overall safety logic. During braking, even if the tensioning system is functioning properly, the elevator may not operate because the governor switch remains deactivated due to bouncing or mechanical impact.

In addition, if a locked tension switch is triggered by the bounce effect after mechanical braking, it may prevent the car from being moved upward through electrical rescue. Since this switch is one of the first elements in the safety chain, it can block the entire rescue process. Therefore, locked-type contacts should be avoided in governor tension switches.