Disconnecting after Breakdown. The disconnecting of one side of a locomotive usually implies that the machine is to continue its journey. It is made necessary by an accident to a cylinder piston, piston rod, steam chest, valve gear, connecting rod, etc. As an example, let it be assumed that a locomotive has met with an accident and one of the cylinder castings is broken. The work that must be done in order that the locomotive may continue its journey is explained in the following:
Method of Procedure. If the crank-pin, connecting rod, and crosshead are uninjured, they need not be removed, but the piston rod should be disconnected from the crosshead and the piston and all removed from the cylinder. If, however, any of the above-mentioned parts are injured and will not function properly, then the main or connecting rod must be taken down on the injured side. In removing the rod care should be exercised to keep all the rod attachments in place as that will be of much assistance when replacing the rod. Next move the piston to the back end of the cylinder as far as it will go and fasten securely by placing wood blocks between the guides so as to fill the space between the cross-head and the end of the guide bars. As a safeguard the wood blocks should be secured by means of rope to prevent them from falling out of position should they become loosened. On some types of locomotives it may not be possible to block the piston in the extreme backward position because of a lack of clearance. In such cases the crosshead should be blocked in the forward position. The back position should be used whenever possible, because if the crosshead became loose in that position and was shot forward it would do less damage than if freed from the forward position. After the crosshead is securely blocked, the valve rod should be disconnected from the rocker and valve stem and the valve moved to its central position so as to cover both steam ports and prevent steam from entering the cylinder. By opening the cylinder cocks and slowly admitting steam by means of the throttle valve, it can be known whether or not the valve is correctly located. If not properly located steam will blow from one of the cylinder cocks. If no steam is discharged at either cylinder cock it is probably correctly set. When it has been correctly set the position of the valve must be secured by clamping the valve stem and wedging or tying it in place. With these changes properly made, the locomotive should be able to proceed on its way with but one side doing work.
In case of injury to both sides the locomotive would not be able to proceed under its own power. The connecting rods may be removed from both sides if the conditions demand it but the side rods should not be removed unless seriously damaged. When the locomotive is proceeding with one side only doing work and it is necessary to remove one or more of the side rods because of injury, the corresponding side rods on the other side should also be removed. Under such conditions the speed of the locomotive should be kept very low because of the effect of the counterbalance on the track.
When both sides are disconnected and the locomotive is being towed back to the shop, attention must be given to proper draining of the various pipes, etc., if the temperature is below the freezing point. It is never necessary to remove the eccentric straps unless it becomes so on account of some injury.
The accidents to a locomotive when in service are numerous. Some may be more serious than others. Space does not permit covering all the possible emergency repairs which it may be necessary to apply. In most cases the character of the breakdown will suggest the remedy.
Table of Contents; Page 180; Page 182; Index