A Historical Overview of the Bulk Grease Delivery Business

For many years grease was shipped only in drums or super-bins loaded into box trailers. In the 1960s some of the large grease users wanted to be able to receive grease in bulk. They wanted it delivered and efficiently pumped into large storage tanks at their facilities.

As early as 1955 one grease manufacturer attempted to ship grease in bulk. They were able to unload about 70% but unable to unload the full amount. During the 60s they tried different techniques to find a way to offload grease more fully.

By the late 60's and early 70's several manufacturers successfully delivered bulk grease in modified cement truck trailers, better know as pneumatic trailers. These were made up of from one to three compartments with sharply slanted cones coming down to a base. The pneumatic trailers were modified in the sense that the discharge pump was mounted directly to the base of the sump, where full suction at the inlet of the pump could be obtained.

People using those trailers were able to make slight modifications making them workable for a number of lower viscosity greases. By it's very nature, grease is designed to strongly adhere to metal surfaces, including the sides of a trailer. Low surface tension and strong adherence make greases very difficult to dispense from a bin or hopper. An air vortex is created in the center of the grease before all of it can slump to the pump suction. Air cavitation of the pump results when the air from this vortex breaks through to the pump suction. All efficient offloading ends at this time. They were therefore able to deliver only 75 to 80% of the product.

By 1973 George Berry developed a new type of trailer, now commonly called a piston trailer. The simplest way to explain a piston trailer is to compare it to a large grease gun. That is, a single long tube containing grease, which has a stabilized piston that forces the product forward by the use of air pressure. Instead of depending on flow and slump into the pump suction, a piston trailer extrudes the grease out of the trailer through a suction hose to the inlet of the pump. The piston is designed to fit tightly against the front of the bulkhead of the trailer and/or tube, so that one can extrude all of the product from the trailer. After completion of unloading, product only exists in the discharge hose and the discharge pump. Normally the discharge hose is three inches in diameter and approximately six feet in length. The pump cavity would hold at most only about two gallons of grease. No more than 5 to 10 gallons is left as a heel. By comparison, hopper or pneumatic trailers often leave 500 to 1000 gallons as a heel.

Since then, this technology has been used to successfully unload many other viscous materials. Many employees of our company have worked with these piston trailers and have learned many important factors to make them operate at maximum efficiency. There have been a number of patents obtained which were assigned to CBW Transport Service, covering improvements made during the 80s.

This has been a quick historical trip covering the adventures of bulk delivery of grease. Find out more about the technology involved by reading our technology page.