Johnson Service Bulletin #900 - Current Coupler for D.C. Generators

Issued May 21, 1962, this bulletin introduced current coupler part 378849 for twin-engine installations. The device allowed two D.C. generators to operate with a single battery without damaging their voltage regulators. Johnson also described its use in installations combining a Model 75 alternator with a generator-equipped engine.

Johnson Motors original blue service bulletin letterhead
May 21, 1962Bulletin No. SB-900
Accessories

SUBJECT:  CURRENT COUPLER FOR D.C. GENERATORS

It is now possible to operate two D.C. generator equipped engines using only one battery. The new current coupler (Part No. 378849) controls the flow of current allowing two generators to operate simultaneously without damaging the voltage regulators or any other part of the electrical circuit.

The current coupler was developed specifically to permit operation of two electric shift 40 h.p. engines (factory equipped with D.C. generators) for the popular twin engine installations. However, the coupler can be used with any twin engine combination using two D.C. generators. It can also be used with one alternator Model 75 and one D.C. generator equipped engine. In this case, only one half of the coupler circuit is used for the D.C. generator. The alternator equipped engines are self controlled and do not require the use of the coupler in the circuit.

The current coupler is available from your Parts Distributor now.
Part No. 378849 - Current Coupler  $12.95 - Less Accessory Discount.

JOHNSON MOTORSOriginal W. W. DeWees signature
W. W. DeWees
Service Department

WWD:eb
NOTE:  Post on your RD (35 & 40 h.p.) RK, V-50 & V-75 indexes.

Referenced part and applications

378849 - Current coupler, originally listed at $12.95 less accessory discount.

Applications discussed: twin electric-shift 40 h.p. engines with D.C. generators, other twin D.C. generator installations, and mixed Model 75 alternator / D.C. generator installations.