Table of Contents
Advertisement
Overheating is any condition by which the temperature of the steam, as it goes to the engine, is above
normal; normal being 400
There are a number of causes for too high a temperature, many of which are due to the carelessness of the man
operating the car.
The function of the thermostat in the new regulation is to govern the ration of fuel and water by admitting an
extra supply of water to the generator through a line, which passes around the flow motor. If the thermostat does not
bypass sufficient water, then the fuel is fed in excess, and the temperature will run too high. If the thermostat is
opening at too high a temperature, the result will be just as bad as from any other source of overheating. The opening
and closing of the water valve depends upon the expansive action of the element in the thermostat, due to the heat of
the steam. If this element becomes bent, it naturally shortens in length. This forces it to expand farther before opening
the water valve, causing a higher temperature. If the stuffing box through which the element works is too tight, there
is the possibility that it will cause the element to bind. The latter is the most common of thermostat trouble. Always
see that the thermostat stuffing box is not so tight but that the element can work freely. It is better to have a slow
steam leak than to have it work tight.
Bear in mind that the correct regulation of temperature and pressure, by the new system, is based on the fact
that the flow motor feeds the fuel and water always in a fixed proportion. Anything that tends to upset this proportion
will upset the regulation. If this idea is kept in view it will greatly simplify the reason for some of the following items
causing an upset in the balance of fuel and water:
1. If the lap fit on the fuel stem becomes worn, it will give the fuel a chance to flow to the burner before the
water can get to the generator. This will cause over-heating, especially at slow speed. The fuel valve is made to fit
very closely for a certain distance, in the hole through which it works. This lap fit is close enough to prevent any flow
of fuel. The stem is supposed to move this distance before the graduated part slips through the hole and the fuel starts,
which gives the water a chance to lead the fuel. It follows that it is not the proper thing to grind a seat on this valve.
The grinding material soon spoils the lap fit, and overheating will result. At high speeds a worn fuel valve is not so
noticeable as the stem moves farther down on the stroke, the ratio again becomes correct.
In replacing fuel valve on the flow motor, if the fuel stem is not screwed into the piston rod sufficiently, we
have exactly the same effect as if the fuel valve were worn, namely, the fuel starts ahead of the water, or at least the
ratio changes. The stem should be screwed into the piston rod until the tension of the spring is felt. Then give it five
more full turns, which gives an adjustment correct enough for practical purposes.
If the stuffing boxes are too tight, the piston, while moving down, as it should be, drags in closing off. This
possibly might feed some fuel after the water regulator has bypassed the water from the generator. Stuffing boxes on
the flow motor should be no tighter than can be tightened with the fingers.
Piston binding in the flow motor barrel would cause a change in ratio. One or two cases have been met with
where this was caused by sand in the water. Most often it is caused by placing flow motor barrel in a vise. If the
piston binds sufficiently, the flow motor will refuse to close, leaving the fuel turned on.
If the spring within the flow motor is weak, broken or too short, it takes a less amount of water to push the
piston down, consequently the fuel would overbalance the water. This is a very rare occurrence, however.
If the vaporizer nozzle is too large it would have a tendency to give the fuel the advantage over the water,
causing a high temperature, The standard vaporizer nozzle advocated by the company should always be used.
Otherwise the fuel and water ratio will be changed.
Items on CHART #1
o
Centigrade. An extreme case is when the coils of the generator are heated to a red heat.
17
OVERHEATING
THERMOSTAT
FLOW MOTOR
Advertisement
Table of Contents
