Piston pumps are a type of dry running reciprocating pump that converts the rotary motor’s energy into the piston’s linear motion within the pump cylinder. Then the piston rod is mounted to an eccentric bearing assembly attached to the motor shaft. It is used to convert rotary energy from the motor into linear piston motion.
When the rod assembly rotates, the piston end tends to wobble. To eliminate this wobbling motion, the piston is sealed to the pump cylinder by a flanged disk cup. This cup along with the pump cylinder forms both a seal and mechanical guide for the piston. It runs without lubrication in contact with low friction, surface-coated cylinder of high heat conductivity.
As the piston goes up and down, air resistance on the upward stroke expands the disk's seal on the piston against the cylinder wall to increase its efficiency, while compensating for the 'wobbling'.
The WOB-L® piston pump technology takes its origin from the principle of operation. In our wobbling piston pumps, the piston rod 'wobbles' inside the cylinder as the crankshaft rotates.
The WOB-L® trademark was patented by Thomas engineers over 40 years ago. They provided a piston compressor radically different from any other design on the market at that time. It still remains a significant innovation in the field of compressor technology today.
Unlike the more conventional articulated piston pump, the WOB-L® has no gudgeon pin (also called wrist pin) connecting the piston rod to the piston. Instead, the piston and piston rod are a single item, usually a single casting.
Oil-less piston pumps are extremely popular in the medical, automotive, and beverage industries.
The pressure vs. flow and vacuum vs. flow characteristics are generally superior to those of diaphragm pumps. WOB-L® piston pumps provide far greater flows at any given pressure or vacuum. They ensure a more consistent and longer operation with the technology allowing a physically smaller pump to be used to perform any given task.
As a piston pump, an inherent characteristic of the design is the failure mode is a gradual fatigue, rather than a catastrophic failure mode which is a characteristic of many other positive displacement pump designs.
Thomas WOB-L® Piston Pumps And Compressors