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which might not be perceptible when new could in the course of time be enlarged by the passage of steam and later
become more noticeable.
Occasionally, the engine will not pull smoothly for a few minutes after starting until the steam has attained its
superheat. This condition is commonly known as when the car is "warming up". The steam not having the elasticity
that it should, will not do as much work in the low pressure cylinder as it does in the high pressure, thereby destroying
the balance between the two cylinders.
By the expression "piston or slide valves cut" is meant a condition where the steam tight surface has become rough or
grooved, owing to the two metals cutting each other. This condition is brought about by poor lubricating oil a lack of
oil or running with the temperature of the car too high. Should a high-pressure valve be cut it allows too much steam
to go through to the low pressure, giving the same condition as leaky simpling valve.
Broken piston rings will also allow too much steam to pass to the low-pressure cylinder, providing the rings,
which are broken, are in the high-pressure. If the low-pressure rings are broken the steam will escape to the condenser
without doing the full amount of work. Either condition destroys the engine balance. Broken rings are usually caused
from a lack of proper lubrication or starting the engine too fast with water in the cylinders.
The items enumerated under this head are causes of vibration under running conditions either simpled or
compound. If the bolts, which hold the engine to the frame, should become loose the engine will bump up and down
on the frame at each stroke of the engine, especially when pulling slowly. Vibration may not be perceptible after the
car has attained speed.
In Models E, F, H, and L which have the engine fly wheel should the bolts holding this fly wheel become
loose it will cause the vibration especially when pulling. The slip joint on the drive shaft fits into the square socket in
the flywheel. As this joint must slip each revolution it is obvious that if the flywheel is loose it will move on its
retaining bolts as it flies around. This same condition can be brought about if the radius rods are so short that the drive
shaft projects into the flywheel socket far enough to bump against the bottom of the socket. This is also especially
noticeable when the engine is pulling hard or accelerating the car on rough roads. The driveshaft square should be
sunk in the fly wheel socket three-eighths of an inch measured on a horizontal center line through the drive shaft.
Lack of lubrication has been treated under Chapter II. The important points as mentioned there especially for
smooth running are the engine, cylinders, and the drive shaft bearings.
Loose rear wheels on the axle may cause vibration to set up at certain speeds. If in looking for the cause of
vibration it is discovered that the rear wheels are loose they should be tightened at once.
If the valves have been taken out and not replaced properly the admission of steam will not take place at the
proper part of the piston stroke. This is enough to cause the engine to pull in a jerky manner, thereby causing it to
shake the car. (See instructions for valve setting.) In extreme cases the engine may refuse to start.
Sometimes in changing the engine or having had it out of the car the rod which runs from the reverse lever to
the reverse arm on the engine frame may be too short. In this case when the reverse lever is in full stroke notch the
valves are running on cut-off. No steam engine will pull smoothly at slow speeds if running on cut-off, especially if
the valve gear gives an increased lead with the shorter cut-off. In cases where the reverse rod is short the engine may
vibrate until the car picks up speed and then runs as smoothly as could be desired. To test this move the reverse lever
beyond the reverse notch of the quadrant while the engine is running. It should not move past this notch, the width of
the latter, before the lever begins to kick. The best way is to adjust so the lever will kick just back of the full stroke
notch on the go ahead and will cease when dropped into the notch. This insures that the valves have full travel at slow
speeds and if it is then desired to work the valves on cut-off at high speeds the valve gear may be hooked up.
A broken ball in the crankshaft bearings or rough bearings caused from lack of lubrication may cause the
engine to vibrate. There is no way of telling this fact without proper examination.
ENGINE VIBRATES EITHER SIMPLED OR COMPOUND
35
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