WOB-L Piston Technology is incorporated in various Q-VAC miniature manual control
by a Fixed Piston
WOB-L piston pumps work to reduce a volume by a fixed
crank-driven piston within a cylinder.
Technical Overview - WOB-L
- Compact, reciprocating design for vacuum or pressure
- Oil-less, non-lube piston and cylinder
- Lightweight die cast aluminum components
- Balanced for low vibration operation
- All wetted aluminum parts treated for corrosion
protection from moisture
- Long life, high performance piston seal
- Permanently lubricated bearings
The WOB-L principle has a unitary piston rod that 'wobbles' inside the cylinder as
the crankshaft rotates (See
Animation). Taking its name from its principle of operation, the WOB-L
trademark was patented by engineers working at Thomas forty years ago. They
provided a piston compressor radically different from any other design on the
market at that time and 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 (wrist pin) connecting the piston rod to the piston.
Instead the piston and piston rod are a single item, usually a single casting.
The piston rod is mounted to an eccentric bearing assembly, which in turn is
mounted to the motor shaft to convert rotary energy from the motor into linear
motion of the piston within the cylinder.
The piston is sealed to the cylinder by a flanged disk
cup, that forms both a seal and mechanical guide for the piston. It runs without
lubrication in contact with a low friction, surface coated cylinder of high heat
conductivity. As the piston is driven 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 'wobble' action.
The oil-free operation and exceptional performance
characteristics make the WOB-L piston extremely
popular in a variety of industries. 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 designs.