Door Lock Repair and Maintenance
Door locks should be cleaned and oiled at regular intervals, at least once a year.
There are two main types of locks for interior doors; these are mortise locks and rim-locks. Mortise locks are the type that fit into recesses cut into the woodwork of the door. Rim-locks are the kind which fit on to the face of the door.
Both types of locks should be removed from doors for cleaning and for repairs. To remove a mortise lock the door handles should first be removed; with knob-type handles removal is done by releasing a small grubwhich secures the knob to the square shank, which passes through both door and lock. With the lever type it is necessary to remove the complete fitting on one side of the door to extract the shank before removing the lock. Mortise locks are removed by loosening the through the face plate on the edge of the door. Once these screws and the shank are removed it should be found an easy matter to lever the lock from the frame.
Rim-locks are removed from doors by loosening and removing all the visible screws on the covering case of the lock. Access to the mechanism of the lock is obtained by removing a side plate in the case of a mortise lock and a back plate in the case of a rim-lock. Both types of plates are held in place by small-bolts. Care should be taken in removing plates to prevent the mechanism springing from the body of the lock. With complete removal a sketch should be made of the method of assembling the different parts. This is essential before dismantling the mechanism.
The simple mechanism of a typical lock is illustrated (right). It will be seen in the image that the lock contains two springs. One of these actuates the sliding bolt that is controlled by turning the door-handle. The other spring actuates the locking bolt, which is operated by turning the key. If either of these is broken, all the parts of the broken spring should be collected and produced when purchasing a new lock spring — springs are obtainable from most local hardware merchants.
It will be appreciated that there are dozens of different makes of locks, each with springs of slightly different shapes, and it is essential to produce the broken parts of the old spring when buying a new one. All the parts of the mechanism should be removed from the case, any rust removed with a soft wire brush and the parts and the inside of the case wiped over with an oily rag before re-assembling the parts and refitting the lock to the door.
Tumbler locks of the ‘Yale’ type very rarely need attention although the bolt may be occasionally oiled. Repairs to this type of lock are best carried out by an expert as this is not really a job for the handyman.