VENDING SECURITY


Preserving lock functionality for vending machines


Preload is a little known, understood or considered factor when selecting and installing an electronic


latch. When talking about preload it is important to understand what preload is and how it impacts a locks ability to function properly. This can be an important consideration in vending machine security. Camlock marketing manager Victoria Brooks explains


WHAT IS PRE-LOAD? Pre-load, sometimes referred to as side load, on a lock refers to the amount of force or pressure that is applied to the locking mechanism from the side, rather than directly in line with the lock. When a lock is installed, it is designed to withstand a certain amount of force, however, if a force is applied to the lock from the side in a consistent manner, this can create pre-load, which can cause damage to the lock. If this happens frequently enough it can affect the locks functionality, which ultimately impacts operation and security.


HOW PRE-LOAD OCCURS When pre-load is applied to an electric lock the force required to open it can vary with different factors, such as a misaligned door or frame, an improperly installed strike plate, or, it may come from a designed in factor such as a rubber seal. In some cases, there is not the means to relieve pre-load, for example, it may not be possible to change a rubber seal. A rubber seal on a door will act differently if the temperature is -5 degrees compared to +20 degrees, therefore a lock needs to not only withstand the temperature itself but the


contraction and expansion of a rubber seal caused by temperature fluctuation, which may cause pre-load as a result. Surface structure can also impact pre-load. For example, if a vending machine is placed on tarmac without a durable surface or proper foundation, which is possible in some public areas, there is a possibility of the unit subsiding on hot days when the tarmac softens. This subsidence could cause the machine to twist and the door to misalign. Misalignment can also occur as the unit ages, through repeated use, or continued slamming, which may cause it to become too tight or too loose. In these cases, only a very slight shift is required to have a major impact on pre-load and locking function. Tampering and attempted forced entry can impact pre-load. If


attempts are made to pry open a door with an electronic lock, the force applied can bend or break parts of the lock or surrounding components causing side load pressure. Understanding the application, constraints, and environmental factors before installing a lock is an important step for ensuring a latch will function optimally in situations where pre-load may be an issue.


THE EFFECTS OF PRE-LOAD ON AN ELECTRONIC LATCH When pre-load is applied to a lock it can reduce functionality of the locking system which can lead to issues with the door operation. Electronic locks, like any mechanical or electronic device, have certain tolerances and limitations and pre-load pressure can potentially affect them in several ways, depending on the design and build quality of the lock, such as: Jamming or sticking: Excessive sideload pressure can cause components within the lock to jam or stick. This may prevent the lock from functioning correctly, making it difficult or impossible to unlock. Component damage: Electronic locks contain sensitive electronic components and excessive pressure, or force applied to the lock can damage both the electronic and mechanical components, leading to a malfunction or complete failure of the locking mechanism.


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