a. Field of the Invention
The present invention relates generally to signaling lanterns used in the railroad industry, and, more particularly, to a trainman's lantern having both axially and radially directed illumination.
b. Prior Art
Trainman's lanterns are specialized lighting apparatus used in the railroad industry for purposes of both signaling and illumination.
In particular, trainman's lanterns are used to transmit signals from the brakeman or switchman to the engineer in the locomotive, when coupling/uncoupling cars, moving on to switches and sidings, and so on. Modern lanterns have their origins in the oil lanterns of the 19th century, and so many of the signals now in use (e.g., swinging the lantern through an arc with the arm lowered) were developed on this basis, with the limitation that the lantern needed to held generally upright. Still other signals evolved with the later adoption of electric lanterns. Furthermore, in addition to signaling, the trainman's lantern must provide general purpose illumination in order for the brakeman to read numbers and information on the cars, to see when walking on the crushed rock ballast, and so on.
This combination of functions has given rise to certain design requirements. First, the lantern must project a degree of illumination in a lateral direction that will be visible to the engineer when the lantern is held/swung in a vertical orientation. It must also have a concentrated “spot” beam that can be used for other signaling as well as for general purpose illumination. Furthermore, the lantern is generally required to have a bail-shaped handle that will not only allow it to be swung from side-to-side as described above, but which will also allow it to be carried over a long shift without excessive fatigue.
One example of a previous trainman's lantern having these characteristics is the Starlite™ model 292, available from Star Headlight & Lantern Company, Honeoye Falls, N.Y., USA. This lantern has a battery case that is supported from a bail, with two incandescent bulbs being mounted at the lower end of the case. The first bulb is mounted within a small parabolic reflector covered by a clear shield, similar to a conventional flashlight. The second bulb protrudes from the end of the case and is exposed so that it can be seen from the sides; a ring projects below the case on struts to protect the exposed bulb from damage.
Although they meet the foregoing requirements (i.e., illumination and signaling) in a general sense, prior lanterns of this type have not been wholly satisfactory. The single exposed bulb is non-directional, and when viewed from the side is inadequately bright to be seen by the engineer at long distances (e.g., at the end of a long train, or “consist”); moreover, at certain angles light from the bulb is blocked by the protective struts. However, using additional bulbs for greater brightness and visibility is not a viable solution due to increased drain on the battery: The lanterns are often kept lit throughout nighttime hours, so that using additional bulbs would mean that in many instances the battery would be dead before the end of the shift. Even with existing two-bulb lanterns, each operating region of a major railroad consumes several thousand batteries every night, at considerable cost.
Other deficiencies of traditional trainman's lanterns include a weak and poorly distributed main “spot” beam and inadequate durability: for example, the struts that support the guard ring around the bottom of the lantern described above must be relatively narrow in order to avoid even worse blockage of the bulb, so that the protective cage is relatively fragile and is smashed with alarming regularity.
Accordingly, there exists a need for a trainman's lantern that provides effective, 360° lateral illumination for signaling when held in a vertical orientation. Furthermore, there exists a need for such a trainman's lantern that provides such illumination with sufficient brightness that is visible at extended distances. Still further, there exists a need for such a lantern that provides such illumination without excessive battery drain. Still further, there exists a need for such a lantern that provides a bright, well-distributed main, “spot” beam for purposes of both illumination and signaling. Still further, there exists a need for such a trainman's lantern that is durable and resistant to breakage in normal operating conditions.