Original U.S. WWII B-24 B-17 Homelite Auxiliary Generator Model HRU-28

Item Description

Original Item. Only One Available. Officially known as the HOMELITE AUXILIARY POWER PLANT, Type C-10, Model HRU-28. The Homelite Model HRU-28, 2000 watt. 28.5 volt gasoline engine driven generator is installed just forward of bulkhead No. 4.0 on the left side of the airplane, on the B-24.

Function: This unit is for recharging the batteries while the airplane in on the ground or for an auxiliary source of electrical energy for the main system during flight.

This example appears to be complete and in very good condition. However, we have no idea if it runs and have not tested it.


1. Supplementary Base Installation
(a) Base is to be installed, open side of channel up, so that Power Plant will be level when plane is in taxiing position.
(b) Drill four mounting holes in channel of supplementary base locating these holes as necessary to meet plane structural members.
Note: A locating fixture shall be used to hold supplementary base in position while fastening in place. This fixture should be designed for attachment to the supplementary base by means of the four tapped holes (11 1/4" center to center width and 23 center to center length) as supplementary base is not sufficiently rigid to maintain these dimensions before fastened in place (c) Fasten supplementary base in position.

2. Place unit is position on supplementary base and fasten with four screws.

3. Connect flexible exhaust line (not a port of Power Plant) to tail pipe of auxiliary muffler to lead exhaust gases outside.

4. Connect Fuel Tank Vent Line (not a part of Power Plant) to Fuel Tank Vent Connector.

5. Remove voltage regulator housing cover and attach voltage regulator (not a part of Power Plant) by inserting prongs in clips at front, or engine end and snap rear clips in place. Replace cover.

6. Connect receptacle on Power Plant to plane wiring in accordance with wiring diagram.

7. Fuel and Oil.
(a) Thoroughly mix 1/2 pint lubricating oil, Spec. 2-91A, Grade 62 SAE-30 with each gallon of gasoline and then pour into fuel container (capacity 1 gallon). To measure the oil, fill the container cup four times (capacity 1/8 pint). Lubrication for the entire engine is obtained by mixing oil gasoline, and it is extremely important that the oil be thoroughly mixed with the gasoline. Gas of 70 to 100 octane is satisfactory, therefore regular ships gasoline is usable.
(b) The generator end requires no lubrication.

8. Starting

(a) Place shut-off valve on top of fuel container to "ON."
(b) To Choke: Pull all the way up on plunger button on priming pump (on top of air cleaner) and release two or three times. In cold weather operate plunger 5 to 8 times.
(c) See that equalizer switch on control box is in Off" position unless main engines are running.
(d) Depress starting switch on control box and release as soon as engine starts.
(e) After engine starts, it may be necessary in cold weather to keep operating the carburetor priming pump at short intervals when the engine falters, until it warms up sufficiently to run smoothly, this should take about one minute.
(f) If the engine does not start within 5 seconds after following above procedure, is may be flooded. To relieve this condition open drain cock on crankcase and turn over engine for a few seconds, by depressing starting switch, to expel raw gas. Close drain cock and depress starting switch.

(g) Emergency Manual Starting. If batteries are dead, the engine can be started manually by following preceding instructions (a), (b), and (c), and then winding starting rope on starting plate, in direction of arrow. Brace one hand on unit and pull rope hard to give a quick spin to engine. Repeat if necessary until engine starts. If necessary, follow instruction on choking, preceding paragraph (e), and if does not start, see instructions on flooding in preceding paragraph (f).

(h) Summarized, the Starting Procedure is as follows:
(1) Prepare fuel and oil mixture;
(2) Pour fuel mixture into fuel container;
(3) Place shut-off valve in "ON. position;
(4) Choke;
(5) Set equalizer switch, if required; and
(6) Depress starting switch or start with rope manually.

9. Operation:

After the Power Plant is started it should require no further attention than refueling and setting equalizer switch to "ON" position if it is desired to charge batteries in parallel with main engine generators while main engines are running. If main engines are not running keep switch in "OFF" position. Correct voltage is maintained automatically by voltage regulator mounted above generator yoke. In normal operation the voltmeter will register approximately 28.5 volts, but if batteries are under heavy load, a lower voltage will be registered.

10. Stopping.
(a) To stop turn shut-off valve on top of fuel container to OFF." The unit will run for approximately 1/2 minute until fuel is consumed in carburetor and sump on bottom of fuel container.
(b) For emergency stopping or if unit is to be restarted soon, press red stop button on magneto stator plate and hold firmly until engine stops.

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