4. POWERING EQUIPMENT 
4.1 ROTATING EQUIPMENT 
a. Inspect commutators and collector rings on all machines to see that the surface is 
smooth and polished. 
b. Check brushes on machines to see that they move freely and make firm and even 
contact with the commutator or collector rings. Keep a spare set of brushes on hand for each 
machine. 
4.2 STARTING EQUIPMENT 
Check time-delay relays to see that they operate at the proper time intervals indicated 
in Figure 50. 
4.3 BATTERY CHARGER 
Lubricate fan motor once a year and if charger is operated in dusty location, blow out 
dust and dirt as often as required. 
4.4 BATTERIES 
4.4.1 Charging 
To protect rotating equipment which is subject to the full charging voltage, this 
voltage should be limited to 50 volts. The charging rates to be used when operating the 
models is posted on the battery charger. 
If individual cells are removed from the tray, it is essential that the cells be 
supported before charging. This may be done by placing stiff fiberboard or plywood on the end 
faces of the cell or group of cells, parallel to the plates within the cell and clamping firmly, 
as with a C-clamp. Never charge an unsupported cell or cell group without lateral support. 
If the battery is on constant float or trickle charge, the charger should be 
adjusted, with the battery in a full charged condition, so that the battery voltage will be 
Maintained between a minimum of 1.37 and a maximum of 1.39 times the number of cells in the 
battery (49.3 to 50.1 volts for a 36-cell, 48-volt battery, etc.). This will keep the battery in 
a charged condition and minimize the frequency of water additions. 
4.4.2 Electrolyte 
The electrolyte in this battery is a solution of potassium hydroxide (KOH) having 
a normal specific gravity of 1.300 at 72°F. It has a freezing point of —-80°F. The specific 
gravity of the electrolyte does not change appreciably between charge and discharge. 
IV-7 
