Power washing apparatus

A portable pumping apparatus for high-pressure washing application comprising, in combination:

• (a) an outer, electrically insulating shroud having a liquid inlet port and a liquid outlet port;
• (b) an inner, single-wall, liquid impervious, motor housing having a hollow interior and generally concentrically disposed within said outer shroud and formed from a material exhibiting high thermal conductivity characteristics, said outer shroud and inner, single-wall motor housing being spaced to define an annular chamber therebetween and joined along a mating interface to seal said hollow interior;
• (c) electric motor means supported entirely within said hollow interior of said motor housing and totally isolated from liquid being pumped, said motor means having an output shaft;
• (d) a transmission housing integrally formed on the exterior of said inner housing and concentrically disposed about said output shaft of said motor;
• (e) speed reducing gear means disposed within said transmission housing and coupled to be driven by said output shaft of said motor;
• (f) gear pump means coupled to be driven by said speed reducing gear means at a speed which is substantially less than said output shaft of said motor, said gear pump means including a pumping chamber, an inlet port in fluid communication with said annular chamber and said pumping chamber and a pumping chamber outlet port in fluid communication with said pumping chamber;
• and
• (g) means for introducing a liquid to be pumped through said liquid inlet port in said shroud to flood said annular chamber while flowing said liquid through said inlet port of said gear pump means into said pumping chamber whereby heat produced by said electric motor is conducted through said inner motor housing and carried away by said liquid being pumped.