The use of mechanical stokers for locomotives has proved conclusively that stoker firing results in greater hauling capacity, at a higher rate of speed than is obtainable from hand firing. The application of stokers not only increases the operating efficiency of the locomotive, but also promotes fuel economy due to the even distribution of coal over the grate area.
The HT Stoker, as illustrated in Fig. 1, is a typical example of a modern type of Standard Stoker. It is applicable to existing locomotives originally designed and built for hand firing as well as to new power.
Description
The Standard HT Stoker embodies the screw-to-jet feature, in which coal is conveyed from the locomotive tender to the distributing table where distribution is accomplished by means of jet blasts. The stoker consists of five principle units employing a minimum number of parts, thus assuring reliability in service as well as low maintenance cost. The five units are:
- A bunker conveyor unit located beneath the coal.
- A telescopic intermediate unit situated between the bunker and the cab.
- An elevator pipe securely fastened to the boiler backplate.
- A distributing unit fastened to the elevator pipe which includes a steam jet, distributing table and air sealing apron.
- An engine providing the necessary power to drive the conveyor.
The conveyor unit is rigidly secured to the frame and consists of a trough, screw, crusher and gear housing. The length of this unit varies to suit the coal capacity of the bunker and is arranged to permit practically all the coal to feed into the conveyor, through openings controlled by sliding plates at the bottom of the bunker.
The bunker, intermediate and elevator screws, fexibly connected by universal joints, are driven from the rear by a series of gears enclosed in a housing provided with suitable bearings and thrust washers for the rotating parts.
A crusher, located at the forward end of the bunker trough, breaks the larger lumps of coal to a proper firing size and permits the smaller lumps to be conveyed through the crushing zone without further breaking.
The intermediate unit as used with the HT Stoker consists of two telescopic conduits, one flexibly connected to the bunker trough, the other to the elevator pipe by ball and socket joints. The screw within the conduit is also flexibly connected to the bunker and elevator screws. This construction provides for sufficient flexibility to allow for the maximum curvature through which the locomotive mat pass without interfering with the operation of the stoker.
The elevator pipe and screw are connected with the intermediate unit and screw just beneath the cab floor. From this point the elevator pipe extends upwards through the floor and its upper end conforms to the contour of the lower half of the firehole opening. The pipe requires very little space in the cab and does not interfere with hand firing and neither it nor the distributing table interferes with ready entrance to the firebox.
The distibuting jet is fastened to the elevator pipe by two bolts and is provided with jet holes of appropriate diameter and angularity for distributing the coal. These holes are divided into five groups for serving different sections of the firebox and each group is controlled by a seperate valve in the jet manifold as illustrated in Fig. 6.
The distributing table is hooked on to the distributor jet and held in position by two pins. The deflecting ribs on the top surface of the distributing table in conjunction with the distributor jet and the adjustable vanes (in the upper portion of the elevator pipe) provide for sufficient flexibility to distribute coal to any part of the firebox. To protect the distributing table from over-heating, cooling air is deflected against its underside by means of an air sealing apron which is fastened to the skirt of the table and fitted to the inside backplate.
The stoker is driven by a double-acting, two-cylinder, variable speed, reversible steam engine, Fig. 2. All working parts are completely enclosed and are lubricated by the splash system, except the valves and cylinders which receive oil from a lubricator.
The engine is reversed by a manually operated valve and its movement interchanges the functions of the steam intake and exhaust ports of the engine, thereby eliminating the necessity for double eccentrics and reversing gear.
The engine and stoker can be operated in reverse, but only a few turns in the reverse direction are necessary to relieve a jam or an obstruction.
The stoker can be located in various positions, on the locomotive, on the tender or in the case of Garratt type locomotives conveniently under the bunker.
When the stoker engine is on the locomotive, it is connected to the stoker by a sliding shaft and universal joints, thereby providing the necessary flexibility. With the tender application the sliding shaft is connected directly to the pinion shaft by a universal joint.
The tender application is particularly adaptable when the weight on the trailing truck journals has reached the permissible limit or if the design of the locomotive will not permit the engine to be located on the locomotive.
The general operation of the stoker is the same for all applications and in each instance the reverse valve is located near the stoker engine.
The reverse valve used to control the direction of rotation of the stoker engine is an ordinary piston type valve manually operated by means of a handle and suitable lever connections. It has three distinct positions: forward (down); reverse (up); neutral (central).
When the valve is in the forward position, Fig. 3, steam from the turret enters opening No. 1, passes around the valve spool to outlet No. 2 and thence to the stoker engine cylinders. The exhaust enters opening No. 3 and passes through the valve spool to opening No. 4.
In the reverse position, steam enters opening No. 1, passes around valve spool to outlet No. 3 and thence to the exhaust steam chamber of the stoker engine, thereby moving the pistons in the reverse direction. The exhaust steam now enters the valve through opening No. 2 and passes through the bottom portion of the valve to opening No. 4.
In neutral position, the valve spool stops the flow of live steam from entering the stoker engine cylinders by closing the passage from opening No. 1 to openings Nos. 2 and 3.
It should be noted that by changing the position of the reverse valve, the engine valves are changed from inside admission in forward operation to outside admission in reverse.
Coal from the bunker drops by gravity into the trough and is conveyed to the distributing table by three cast steel conveyor screws flexibly connected at the ball sections of the trough and elevator pipe. To aid in the moving of lump coal and to prevent the overflow of coal at the crushing zone the bunker screw flights are segmented, thus overcoming a condition which is common with screws having uninterrupted flights. The bunker and intermediate screws are connected at the ball section of the trough by a universal joint while the intermediate and elevator screws are connected at the ball section of the elevator pipe by a double universal joint link. The construction of the link provides the necessary flexibility between the screws and permits the coal to move through the elevator pipe ball section without packing or grinding.
The elevator screw, as will be noted in Fig. 4, extends approximately to the top of the elevator pipe and delivers coal, in free and loose form, to the distributing table. The distributor jets, together with the adjustable vanes in each side of the upper end of the elevator pipe, provide an efficient method of controlling distribution of coal over the entire grate area. The jet pressures are controlled by five valves located in the cab within easy reach of the fireman. The amount of coal delivered to the firebox is governed by the speed of the stoker engine and is manually controlled by the fireman.
Locomotive Stoker Firing
It has been wisely said, “A task well begun is a task half done.” This truism applies particularly to stoker firing.
The stoker of today will fire a locomotive under all circumstances if properly manipulated and its capacity for maintaining steam is far beyond hand firing. It is, however, not automatic; it depends upon human hands and intelligence for proper and efficient operation. The stoker will convey the coal fast or slow, depending upon the adjustment of the operating valve in the steam line to the stoker engine, and will distribute the coal to any part of the grates at the will of the fireman, depending upon his judgement in the manipulation of the distributing valves.
When a locomotive is ready to leave the shed, the fire should be in good condition, free from banks, clinkers and excessive ash accumulation on the grate. The preperation of the fire before starting the stoker, which should be tested before leaving the shed, should be done by hand and the fire should be heavy enough to withstand the fierce draught created when starting the train. Avoid a thick fire, however. Ensure that the portion of the grate under the distributing table is well covered with coal. Also, when preparing the fire, break the coal to 3″ size or smaller. Large lumps produce an uneven fire that will give trouble on the road.
Light firing with constant distribution of the coal to cover entire surface of the fire bed will produce the highest combustion efficiency. Heavy firing or racing the stoker intermittently leads to improper and incomplete combustion, clinkered fires, excessive black smoke and waste of coal.
Handling of the rocking grate in connection with stoker firing is an important factor. The sections of the grate should not be shaken violently while locomotive is working, on account of the light fire bed carried with the stoker. They should be rocked gently and as frequently as may be necessary, depending upon the type of grate in use, in order to keep the ash accumulation underneath the fire bed down to a point where it will not interfere with the uniform flow of air necessary to complete combustion. If it is necessary to shake the grate heavily to dispose of excessive accumulation of ash and clinker formation, it should be done while locomotive is standing or drifting, or at places where the locomotive is lightly worked and the maximum boiler pressure is not required to handle the train. Holes in the fire are very apt to form from too heavy rocking of the grates while the locomotive is working hard and in many instances are the cause of loss of pressure before the fireman can locate the hole and stop the inrush of cold air.
If holes do occur or the fire becomes uneven it is essential that the fire be put right by means of hand firing. Attempting to cure a bad fire by means of the stoker alone will assuredly end in disaster.
Occasionally, conditions are encountered which necessitate readjustment of the distributing devices in order to maintain proper distribution of the coal. Some of these are: grade and weight of coal supplied; condition of coal, wet or dry; thickness of fire bed; change in the combustion rate or draught caused by change of cut-off. Irregular draught conditions through the grate caused by bars not being properly spaced and adjusted, improper setting of the brick arch and holes in the arch all have their influence on the draught and affect distribution. Therefore, occasional inspection of fire conditions and distribution is essential. This will enable the fireman to take timely action to correct improper conditions that may be in the formative state and can be corrected by a slight adjustment of the distributing valves. Generally, if one adheres to the principles embodied in good hand firing, success in stoker firing will likewise prevail.
The driver’s handling of the regulator and cut-off, which control the admission of steam to the cylinders, has its effect on successful performance of stoker fired locomotives. Close co-operation between the driver and fireman is very important. The fireman should be informed as to any movement out of the ordinary which imposes extra heavy work on the locomotive and requires special attention, particularly if he is not familiar with the road and operating conditions. The driver should not start without asking the fireman if the fire is ready, as a light stoker fire is easy to upset when starting a heavy train. The engine should not be worked at longer cut-off just because the stoker will deliver the coal and the pointer on the steam gauge registers the maximum pressure, but should be handled in the shortest cut-off possible to haul the tonnage and maintain the schedule. Remember that the boiler’s efficiency falls at high rates of tiring. Twice as much coal does not mean twice as much steam. Whenever the maximum output of the locomotive is needed, it can be had at all times, as all stoker fired locomotives can be worked to capacity regardless of the physical limitation of the fireman.
General Suggestions to Fireman
Important — Under no circumstances allow coal to build up around the distributing table, thus restricting the flow of cooling air and materially shortening the life of the table.
The same general principles that pertain to fire conditions under hand firing apply to stoker firing, that is, to maintain a thin, level, bright fire and uniform distribution of fuel over the entire grate surface.
See that fire is clean and in good condition before leaving the shed.
Do not feed too much coal — carry a light fire. The stoker should be regulated to deliver a constant supply of coal to the firebox, but only enough to meet the demand on the boiler for steam.
Do not allow rock, iron, wood or other foreign matter to be fed into the stoker if it can be detected in the coal and removed before it enters the conveyor.
Before taking coal, while en route or at a shed, see that all bunker slides are closed.
See that the stoker is lubricated at recommended intervals.
Operating Instructions
Lubrication
Before leaving the shed, check the oil level in the stoker engine bed. Keep oil to level of pet cock, or to “full” mark on the dipstick, No. 7, to ensure proper lubrication of all parts within the engine bed. When additional oil is necessary, apply at filler plug, No. 8, using engine oil.
A compartment oil box, No. 9, and grease gun connections, Nos. 14 and 42, supply the lubricant necessary for the various conveyor trough bearings. The oil box also provides lubrication for the universal joints. Fill each compartment with engine oil (do not use cylinder oil) at the beginning of the trip.
On stoker engines fitted with mechanical lubricators the shed staff should set the feed to 0·25 c.c. per revolution of the ratchet shaft. Check the oil level in the reservoir, and add cylinder oil if required. In some cases this lubricator also feeds the conveyor ball joints, though sometimes they are grease lubricated. On some locomotives the oil is supplied from the main locomotive mechanical lubricators. Where a sight feed lubricator is used the feed should be set to feed three drops per minute.
Operation
To start the stoker, first open turret valves admitting steam to engine and jet lines, Nos. 1 and 2 respectively; next open main jet valve, No. 3; then open each of the five manifold jet valves, No. 12, separately to see that jet holes are free from obstruction. Now set the jet valves as follows:
- Close main jet valve.
- Open left and right front valves one full turn each, taking reasonable care that both valves are open the same amount. Open left and right back valves three-quarter turn each. Open main jet valve slowly till about 50 or 60 lb./sq.in. pressure is shown on the front jet gauges. (The operating pressures used on the road depend on the characteristics of the locomotive to which the stoker is fitted and are determined by trial when the locomotive goes into service). The front jet gauges should now show the same pressure to within a few pounds or so. If they do not, then either a gauge is defective or a jet is blocked.
- Open the “fine coal” jet valve to give a pressure of 10 to 20 lb./sq.in. The pressure shown on the front jet gauges will fall slightly as this is being done so open the main jet valve a little more to compensate for this.
Note — If the coal is wet, the “fine coal” pressure should be high — 20 pounds or more — to keep the distributor table clear of coal that tends to coke fast. If the coal is dry but is fed on to the distributor table in fairly large pieces, the “fine coal” pressure should again be high. If the coal is dry and contains a lot of “fines,” the pressure should be low — 10 pounds or less. With high “fine coal” pressures it is generally advisable to use slightly lower than normal pressures on the jets to the front corners. Since the left and right back corner jet valves are not open as much as the front corner valves the pressure to the back corners will be lower. This is intentional since only sufficient pressure to blow the coal from the corners of the distributor table is required.
Note position of the operating lever, No. 4, for stoker engine reverse valve and see that it is in forward position. There are three positions: full travel downward is “forward”; full travel upward is “reverse”; centre notch is “neutral” position.
Open stoker engine valve, No. 5, slowly to permit cylinders to heat up and condensation to exhaust through automatic drain valve, No. 15. This valve will close when condensate has been released. The stoker engine valve can now be regulated for the desired speed. Booster valve, No. 6, should be kept closed except in cases where it is necessary to increase the steam pressure to stoker engine rapidly in order to crush an exceptionally hard lump of coal. As soon as possible, valve No. 6 should be closed and stoker operated with steam through valve No. 5.
Pull the first slide plate forward to admit coal to the conveyor. Open firedoor for observation and as the coal reaches the distributing table, No. 16, adjust the manifold jet valves, No. 12, to get an even distribution of coal over the entire grate area.
The vanes at the right and left sides of the mouth of the elevator pipe control the distribution of the coal on to the distributing table and must be set as determined by road trials.
The rate at which coal is delivered to the distributing table can be observed through the peep holes in the top portion of the elevator pipe. In normal operation the pressure on the stoker engine gauge, No. 31, will vary between 10 and 25 pounds. To prevent undue strain on the stoker mechanism a relief valve, No. 19, is located in the steam line to the stoker engine. When a hard lump of coal checks the speed of the stoker, the pressure in the engine cylinders will gradually increase to approximately 110 pounds at which point the valve will open. If the relief valve opens and continues to blow, it indicates that the stoker has stalled.
Removing Obstructions
If the stoker stalls, in nearly all instances an obstruction will be found at the crusher zone (located in the bunker trough). To relieve it, reverse the stoker by placing the operating lever in upward or reverse position. If, after repeated reversal, the stoker will not operate normally, it is an indication that the obstruction is too large to pass through the crusher, No. 38.
Note — In some applications the stoker engine exhaust is led into the ashpan and occasionally the exhaust pipe becomes blocked with ash, thus causing the stoker engine to stall.
IMPORTANT: When removing an obstruction from the conveying system be certain that steam valves, Nos. 5 and 6, are shut tight and that the operating lever, No. 4, for the stoker engine is in neutral position.
To remove a stoppage at the crusher, reverse the stoker in the manner previously described forcing the obstruction out of the crusher after which it can be removed from the conveyor. Should it be wedged so tightly that the stoker cannot be reversed, the crusher can be taken out by removing the two bolts which fasten it to the bunker trough.
Taking Coal and Termination of Trip
Before taking coal en route all bunker trough slides should be closed. They should also be closed before arriving at the shed and the stoker kept in operation for a short time thereafter, so that the conveyor may be empty on arrival. This is to prevent wet coal from freezing in the winter; also to permit the shed men to make proper inspection.
On arrival at the shed close stoker engine valve, No. 5, and place stoker engine reverse valve in “neutral” position. Leave turret valve open so that steam can blow through the bleed holes in the main jet valve, No. 3, and the five manifold jet valves, No. 12, which should be closed. It is important that the bleed holes be clear to ensure a small flow of steam over the distributing table to keep it cool while the fire is ”banked.” This same precaution should be taken when standing in a siding or drifting on long grades or at any other time when the stoker is not in operation.
Note condition of distributing table, No. 16; if burned or warped so as to affect distribution, report for replacement at the shed.
Report any other defect in stoker mechanism.
Running Shed Inspection
The stoker should be inspected as other parts of the locomotive on arrival at the terminal. Run the stoker with the slide plates closed to ascertain its general condition.
To ensure proper lubrication of all parts within the stoker engine bed, keep oil to “full” mark on dipstick, No. 7. When additional oil is necessary, apply at filler plug, No. 8, using a good quality engine oil. Drain oil every thirty days through drain cock, No. 13. Flush out every ninety days.
If too frequent additions of oil to the engine bed are required, check the packing, side bearing oil seals, or engine bed covers for oil leaks. Bearing wear should not exceed ·015″.
Drain cock, No. 13, should be opened at least every two weeks to release any water which may be in the engine bed due to condensation or worn packing.
Inspect gear housing every thirty days, supplying additional lubricant, if necessary, through feeder pipes, Nos. 14 and 42. The pinion shaft bearing should be lubricated frequently at connection No. 42.
Be sure that the automatic drain valve and relief valve, Nos. 15 and 19, located in the steam line to the stoker engine, are operating properly. Drain valves close at 5 to 8 lb./sq.in. and relief valve opens at 110 lb./sq.in.
Special attention should be given to the distributor jet, No. 35, to see that the jet holes are not blocked or jet pipes leaking.
Make sure that the main jet valve, No. 3, and manifold jet valves, No. 12, have bleed holes and that they are not blocked; i.e., a wisp of steam should blow through the jets even when these valves are closed.
At each washout ensure that the air sealing apron is in place and that the air holes in the underside of the distributing table are not blocked with clinker.
When building fire in the locomotive, do not permit coal to collect on top of or bank around the distributing table. Unless this precaution is taken, the life of the table will be materially shortened.
Drawbar Inspection
Before moving the tender away from the locomotive for drawbar inspection or disconnecting the hind unit on Garratt type locomotives, operate the stoker for a time sufficient to remove all coal from the conveying system. Then remove the bolts which hold the two halves of the outside rear bowl, No. 30, to the back conveyor trough, No. 26. Slide this trough forward and disconnect the intermediate screw, No. 22, by removing universal joint bolt, No. 43. The tender can now be separated from the locomotive but care should be taken to support the intermediate unit so that it does not drop and become damaged. When recoupling the screws, make certain that the screw flights are continuous or it will be impossible to apply the universal joint bolt.
When the stoker engine is located on the locomotive, the driven section of the drive shaft, No. 27, should be guided into the driving section, No. 28, as the locomotive and tender are moved together for coupling. In all cases where the engine is located on the locomotive this procedure should be followed.
Maintenance and Repairs
Satisfactory stoker operation depends upon proper lubrication and maintenance. Insufficient lubrication, excessive wear, and lost motion will result in a greater amount of steam being required to operate the stoker.
Renewing Piston Rod and Valve Stem Packing
Each piston rod and valve stem has two stuffing boxes, one on the engine bed to prevent the loss of oil, the other on the cylinder block to prevent the escape of steam. Both the piston rod and valve stem stuffing boxes are readily accessible and are packed in the usual manner. The gland nuts are provided with locking devices and after adjustments or repacking, the lock should be set to prevent the nuts from working loose.
Connecting Rod and Eccentric Strap Adjustment
The big ends of the connecting rods and eccentric straps are fitted with shims to provide for adjustment. To take up lost motion, remove engine bed cover and reduce shims in the usual manner. When reapplying castle nuts, be sure cotters are in place.
The eccentric straps, connecting rods, and crossheads can be dismantled without removing the crankshaft. If, however, it is desirable to remove the crankshaft it can be done by taking off the engine bed cover, side bearings and roller bearings.
Renewing Valve Rings
To remove the valve assembly, loosen valve stem lock nut, screw from coupling and withdraw the valve from the valve chamber. After the rings have been applied, place valve assembly in the chamber and adjust the valve travel in accordance with the following instructions.
Instructions for Checking and Setting Valves of Stoker Engine
- Remove both valve chest covers.
- Rotate crankshaft until one of the valves has moved to extreme outward position in the valve chamber. The distance from the face of the valve to the face of valve chest bushing should measure l3/8″. Then turn the crankshaft over until the valve is at the extreme inward position. The distance from the face of valve to the face of valve chest bushing should measure 21/2″.
- If the valve, in its extreme positions, is to these dimensions, then it is correctly set. If otherwise, remove the engine bed top cover plate and adjust the valve position by lengthening or shortening the valve stem.
- If the valve travel does not come to the above dimensions, it is due to excessive lost motion in the eccentric strap or in the connection between the eccentric strap and valve stem. This lost motion should be taken up and the valve set according to above instructions.
- This procedure applies to both valves.
Renewing Piston Packing Rings
Draw piston rod cotter, remove the piston and rod and apply rings in the usual manner.
Removing Distributing Table, Jet or Sealing Apron
When necessary to remove distributing table, No. 16, or air sealing apron, No. 17, remove holding pins, No. 18, on each side of the distributor jet, No. 35. Unhook the table and remove through the firehole. The sealing apron can then be detached by removing the bolts located on each side of the distributing table skirt. When replacing, apply bolts in distributing table, slip the apron into position and partly tighten nuts. Then place the unit on the distributor jet, adjust apron to the inside firebox backplate allowing a small clearance not to exceed 1/4″ between edge of apron and firebox plate. Then tighten nuts securely. Do not fail to replace holding pins in the distributing table.
To replace distributor jet, No. 35, remove distributing table in the manner previously described; disconnect jet pipes, then remove the two bolts holding the jet to the elevator pipe and withdraw through firehole.
Removing Bunker Conveyor Screw
To remove the bunker screw, No. 23, take out the bolts which hold the two halves of the outside rear bowl, No. 30, to the back conveyor pipe, No. 26. Slide this pipe forward and disconnect the intermediate screw, No. 22, by removing universal joint bolt, No. 43. After supporting the intermediate unit, the tender can be separated from the locomotive and the bunker screw withdrawn from the conveyor trough by removing the two bolts which fasten it to the main drive shaft.
It is important when replacing the bunker screw to have the manganese thrust washers, Nos. 39 and 40, which are located between the rear of the bunker screw and the hub of the gear housing, in their proper position. Clearance between the two washers should not be more than 1/8″ and if in excess of this a suitably thick M.S. washer with a square hole in it to suit the shaft should be placed between the end of the screw and the manganese steel washer with the square hole.
When recoupling the screws, make certain that the screw flights are continuous or it will be impossible to apply the universal joint bolt.
Removing Intermediate Conveyor Screw
To renew the intermediate screw, No. 22, disconnect the stoker at the rear bowl as previously described, then remove elevator pipe ball cover, No. 20, and separate intermediate and elevator screws, Nos. 22 and 25, by removing universal joint bolt, No. 37. The entire intermediate unit can then be lifted out of position and dismantled.
Removing Elevator Screw
To renew elevator screw, No. 25, take off elevator pipe ball cover, No. 20, disconnect elevator and intermediate screws, Nos. 22 and 25; raise and support front pipe, No. 24, so that it will clear the ball section of the elevator pipe, No. 21. The tender can then be drawn back permitting the elevator screw to be withdrawn from the elevator pipe. On Beyer-Garratts, the elevator screw can be withdrawn after the intermediate screw and front pipe have been lifted clear of the elevator pipe.
In recoupling the elevator and intermediate screws the flight of the universal joint link, No. 36, should be in a position to form a continuous flight between the two screws and when they are properly connected the marker stars on the screws and link jaws will be in line.
Important — When removing the complete tender unit or elevator pipe for repairs see that they are reapplied in accordance with the application drawing and also make certain that the intermediate bowl centres are maintained, as the satisfactory performance of the stoker depends upon these parts being properly located.
Questions and Answers
Question 1 — What attention should the fireman give the stoker mechanism before starting the stoker?
Answer — Inspect the visible parts to see that the stoker is in good order. Note if the engine crankcase has sufficient oil (keep oil to “full” mark on dipstick); then lubricate such parts of the machine as are not cared for by the running shed.
Question 2 — What parts should the fireman oil?
Answer — The drive shaft universal joints, also the sliding shafts.
Question 3 — How are these bearings lubricated? What kind of oil?
Answer — A compartment oil box is located on the side of the bunker, from which pipes lead to the various bearings. Fill oil box with engine oil at the beginning of the trip. Do not use cylinder oil. The sliding shafts should be oiled by hand, using engine oil.
Question 4 — How much oil should be applied and how often?
Answer — About one-eighth pint per compartment. A few drops on the sliding shafts. Once every four hours unless the bearings indicate by squealing that they are running dry.
Question 5 — How is the stoker engine lubricated?
Answer — The cylinders and valves from a lubricator which may be sight feed or mechanical; the parts within the engine by the splash system.
Question 6 — How much oil should be fed to the stoker engine cylinders?
Answer — Three drops per minute when a sight feed lubricator is fitted, and 0·25 c.c. per revolution of the ratchet feed with a mechanical lubricator.
Question 7 — How are the gears and bearings at the rear end of the tender trough lubricated?
Answer — The gear case is filled with soft grease.
Question 8 — How should the fire in a stoker equipped locomotive be built up and maintained at the shed and in a siding? Why?
Answer — The fire should be built up by hand at the shed and maintained by hand in a siding. During this time you have the best opportunity to observe the general conditions of the fire and make any corrections that are necessary. Break the lumps to 3 inches or smaller when hand firing.
Question 9 — In firing with a stoker should the coal be fed constantly or intermittently?
Answer — The stoker should be regulated to feed a constant supply of coal into the firebox, but only enough to meet the demand on the boiler for steam, which is according to the work done by the engine.
Question 10 — How deep should the fire be carried?
Answer — For best results the fire should be carried as thin as possible for maintaining the required steam pressure. Do not allow fire to build up or bank around the distributing table. Unless this precaution is taken, the table is likely to burn and warp — which condition will interfere with proper distribution as well as shorten the service life of the table.
Question 11 — How should the stoker be started?
Answer — Open turret valves admitting steam to engine and jet lines. Next gradually open main jet valve, then open the five jet valves separately to see that jet holes are free from obstruction. Open stoker engine valve slowly to permit any condensate to escape through automatic drain valve. Place operating lever in forward position and adjust engine throttle valve to run the stoker at desired speed.
Question 12 — How can the speed of the stoker be controlled?
Answer — By the stoker engine throttle valve.
Question 13 — Can the stoker be reversed?
Answer — Yes. By means of the reverse valve in the steam line to the stoker engine.
Question 14 — What damage might be done if the manifold control valve or the distributor jet valves were fully opened suddenly?
Answer — It might crack the distributor jet.
Question 15 — What should be done after the stoker is started?
Answer — Pull the first slide forward to admit coal to conveyor. When coal appears at the distributing table, adjust jet valves to get an even distribution of coal over the entire grate area. The back corner valves should be open about three-quarter turn each and the front corner valves at least a full turn.
Question 16 — How many distributor jet valves are there?
Answer — Five. One for each front corner; one for each rear corner and one for line coal.
Question 17 — Can these valves be set to obtain even distribution regardless of the grade of coal and rate of firing?
Answer — Yes.
Question 18 — How can the flow of coal to the distributing table be observed?
Answer — Through the peep holes located in the top of the elevator pipe.
Question 19 — When the stoker engine relief valve opens and continues to blow, what does it indicate?
Answer — That the stoker has stopped.
Question 20 — In a case of this kind what should be done?
Answer — Reverse the stoker engine a few times and if necessary, use the booster valve.
Question 21 — If, after reversing the stoker, it will not start or will only make one or two turns and then stops again, what does it indicate and what should be done?
Answer — It indicates that a piece of foreign matter, such as iron, has caught in the conveyor. Flush the bunker conveyor trough with water from the coal watering hose and try to work the obstruction through by repeated reversal of the stoker.
Question 22 — Does not the liberal use of water in connection with slack coal have a tendency to plug or clog the stoker?
Answer — No.
Question 23 — If, after repeated efforts, it is found the stoker will not operate, what should be done?
Answer — Close the stoker throttle valve, place the operating lever in neutral position (centre notch) then look for the obstruction and remove it.
Question 24 — Where might the obstruction be found?
Answer — At the crushing zone or the bunker bowl.
Question 25 — How many groups of holes are there in the distributor jet and what parts of the firebox do they control?
Answer — Five (5). One group for each front corner, one for each rear corner and one for fine coal.
Question 26 — If, on opening the jet valves, one or more of these holes are found blocked, what should be done?
Answer — First close all the jet valves but the one controlling the blocked hole. Open this valve wide and try to blow out the obstruction. If the hole cannot be opened in this manner, use the small hook provided for the purpose.
Question 27 — Should the flow of steam through the jet openings be shut off while on the road and when the stoker is not in operation?
Answer — No. To prevent overheating the distributing table there should always be a light flow of steam through jet openings as long as there is a fire in the locomotive and the turret valve must not be closed.
Question 28 — What is the purpose of the air sealing apron attached to the distributing table?
Answer — It directs cooling air against the under side of the distributing table thereby prolonging the life of this part.
Question 29 — Where are the vanes located and what is their purpose?
Answer — In the upper portion of the elevator pipe and they are for controlling the amount of coal delivered to the back corners of the firebox.
Question 30 — Is it necessary to make frequent adjustments of the jet valves or vanes?
Answer — No. After they are once set to give correct distribution they need not be changed unless a bank forms in the fire. However, a change in coal size may necessitate a resetting of the jet valves and vanes.
Question 31 — In case of a bank, what should be done?
Answer — Shake out the bank promptly before it has time to clinker and rebuild the fire by hand. It may be necessary to change the jet pressure, the position of the vanes or both, so that coal will not be delivered to the area where the bank formed.
Question 32 — How are the vanes adjusted?
Answer — By hand levers on each side of the elevator pipe.
Question 33 — What are the duties of the fireman at the end of trip?
Answer — Just before arriving at the shed, close all bunker trough slides so that conveyor may be empty on arrival. When the engine is placed on the shed road, run the stoker in reverse a few revolutions to remove coal from the elevator pipe. Then place the operating lever in neutral position. Close the stoker engine and main jet valves. If the latter valve has not been provided with a bleed hole, it should be left slightly cracked until the fire has been dropped. Do not close the turret valve while there is a fire on the grate.