It is a requirement for operation of a railroad to be able to switch trains from one track to another. A common method of providing the switching capability is to install an electric motor driven switch which functions, by means of a motor driven throw bar or the like to throw switch points so as to control the switching of rolling stock.
Although this type of switching works well for main line and transit operations, for yard applications additional switching features are required. For example, it is common for yard switch machines to have provisions for hand throw to permit local operational personnel to operate the switch.
In the context of operation in very busy railroad yards, in which the railroad stock is being continuously moved in the forward and reverse directions, it is required to move such stock through switches with the switch in the reverse or trailing position. A yard switch machine that will trail without damage is very desirable in that the train operator does not have to stop the train and throw the switch is passage if in the reverse or trailing direction.
For a switch machine with trailing capability, passage of rolling stock through the switch in the reverse or trailing direction will cause the switch to be thrown automatically, that is, without the time delay of a manual switch operation.
However, the traditional or conventional method of providing trailing capability for a switch machine has been to package the required mechanism inside the switch machine. This concept is not desirable for the following reasons: (1) The trailing mechanism is rather large and, as a result, packaging the device inside the switch machine results in either a relatively large profile height for the switch or elimination of other desired switch machine functions. (2) A switch machine with a built in trailing means or mechanism cannot be used for main line and transit operations where trailing is not required. (3) The trailing mechanism, according to conventional construction, has such mechanism built into and integral with a switch machine and is usually packaged on the bottom of the machine to be near the throw bar. Consequently, maintenance and inspection is difficult since the switch machine must be disassembled to reach the interior area occupied by the trailing mechanism.
Accordingly, it is a primary object of the present invention to provide a trailing mechanism that can be used in conjunction with a low profile configuration switch machine. A related object of the present invention is to make the aforesaid trailing mechanism such that it can be placed outside the switch machine configuration.
An ancillary object is to provide flexibility so one can either conjoin the trailing mechanism with the switch machine or not so conjoin. In other words the switch machine stands on its own or can either incorporate or not incorporate the trailing mechanism.
A desirable function of a switch machine or a railroad switch layout is the ability to incorporate lost motion into the trailing mechanism. Switch machines are fixed stroke, or fixed throw mechanisms; they are usually set to the maximum throw that will be required for all switch layouts. A throw of 6.0 inches to 6.5 inches maximum is usually selected. Some switch layouts will require much less throw for the switch layout. A 4.0 inch minimum is common in the industry. Since the traditional switch machine is a fixed throw device set for the maximum throw required, a lost motion means must be provided by either the switch machine or the switch layout itself.
It has been the common practice in the industry to provide the lost motion mechanism in the switch layout and not in the switch machine. This practice results in additional installation cost and maintenance of the lost motion mechanism.
It is therefore, an object of another, different feature of the invention to avoid the additional costs normally involved in installation and maintenance of the lost motion mechanism by, instead, incorporating that mechanism within the trailing mechanism or device.