Door handles are different for a good reason. Although you might think that they all perform a fairly similar function – that of opening a door – they don't. If you think about it for a moment, your front door handle is likely to be different from the sort of thing you'd find in a bathroom, for instance. Door handle designs vary for stylistic reasons, of course, but their principle design ethos is driven by their function. Let's take a closer look at some of the commonest handle designs and examine how each product is arranged for its specific purpose.
A lever latch on a backplate. This is one of the most frequently seen designs in homes and office with good reason. A backplate makes for a firm and secure fixing against the door which means that the lever can be operated many, many times during the lifetime of the product without it becoming loose or placing to much strain on the device's internal mechanism. This is a common design because it tends to be used for internal doorways only. In situations where you want a door to shut and remain closed against a simple latch – with no lock – then a lever latch on a backplate is ideal. Since most buildings have more doors of this type than any other, this door handle the most popular. When the lever is pushed down, a tubular latch or box latch within the handle's backplate is pulled inwards, thereby allowing the door to be opened.
A lever lock on a backplate. Often designed to match the style of a simple lever latch on a backplate, a lever lock door handle differs in one important way. The backplate has a hole in it that normally lies just beneath the lever. This aperture is designed to allow a key to access the locking mechanism inside. Sometimes the backplate is slightly longer in design to accommodate the lock. All sorts of locking mechanisms can be incorporated into such a door handle, but the most usual is a simple mortice lock. This design is often put to use with a back or side door where access from the outside needs to be restricted. However, they are sometimes used for internal doors, as well, perhaps to control access to an office.
A bath lock on a backplate. Unlike a conventional lever lock, a bath lock can only be operated from one side of the door. Furthermore, it requires no key to function. The backplate may be a little larger to allow a twist-and-turn locking mechanism to be accommodated beneath the lever. When turned, the bath lock prevents access from the other side of the door, thus affording privacy for the person who has operated it.