What a Pump Element Is
A pump element is a replaceable plunger, spring, seal, and threaded body assembly that screws into a pump housing. It is not a complete pump, and it does not include the drive mechanism, reservoir, or outlet manifold.
The M20x1.5 element fits a matching port in the pump housing and meters lubricant by piston stroke. The thread alone does not guarantee fit, so confirm piston diameter, stroke, and drive geometry before ordering.
For a broader view of how these components fit into a system, see the pump element overview page or the pump element category.
How the Spring-Return Mechanism Works
The drive presses the plunger out against the spring, pushing a measured volume of lubricant through the outlet. When the drive retracts, the spring returns the plunger to its rest position and the chamber refills.
This spring-return design works well for grease up to NLGI 2 and oil viscosity up to 40 cSt within the stated temperature range. For very cold or very viscous service, a positively driven element may be a better boundary condition.
Spring-return elements are common in automatic lubrication systems where the drive provides only a push stroke. The return stroke depends on the spring, so cycle rate and lubricant resistance affect refill behavior.
The Three Delivery Rates
This element is offered in three delivery rates: 60, 120, and 170 mm3 per stroke depending on model. The per-stroke volume means volume per piston stroke, not per point dose delivered to a bearing.
Choose the rate based on the lubricant demand of the point or group being served. A lower rate suits small bearings, while a higher rate supports larger or faster-wearing points.
The 120 and 170 mm3 versions are also available as separate product pages: EP-120 pump element and EP-170 pump element.
Specifications
| Mounting thread | M20x1.5 |
|---|---|
| Piston diameter | 6 mm |
| Delivery rates | 60, 120, 170 mm3 per stroke |
| Maximum pressure | 280 bar |
| Operating temperature | -35 degrees C to +70 degrees C |
| Flow | 0.8-5.0 cm3/min depending on model and cycle rate |
| Material | Steel body zinc plated with yellow chromate |
| Lubricants | Grease up to NLGI 2, oil viscosity up to 40 cSt |
| Relief valve | Integrated relief valve available on select models |
| Installation torque | 25-30 Nm |
Fitting an M20x1.5 Element
The element screws into a matching M20x1.5 element port in the pump housing. The thread is 20 mm nominal diameter with a 1.5 mm pitch, but thread alone does not confirm compatibility.
Confirm piston diameter, stroke, and drive geometry before ordering. A 6 mm piston with the correct thread may still have the wrong stroke or return style for your housing.
For a similar thread size with different geometry, compare the M18x1.5 pump element. For system-level context, see automatic lubrication overview.
If the port, piston, or stroke is unclear, send the old element details for matching.
Spring-Return or Positively Driven
Spring-return elements rely on the spring to refill the chamber after each drive stroke. This is simple and compact, but refill speed depends on lubricant viscosity and temperature.
Positively driven elements use a mechanical return instead of a spring, which can help in very cold or very viscous service. If your lubricant is near the upper viscosity limit or the environment is below the stated temperature range, consider a positively driven option.
For most grease and oil applications within the declared limits, the spring-return element is a direct replacement component. Always match the delivery rate and drive geometry to the existing housing.
Frequently Asked Questions
Is this a complete pump or just an element?
This is a replacement pump element only, not a complete pump. It includes the plunger, spring, seals, and threaded body.
What does the 6 mm piston diameter mean?
The 6 mm figure is the diameter of the metering piston inside the element. It affects the delivery volume per stroke.
Which delivery rate do I need?
Choose 60, 120, or 170 mm3 per stroke based on the lubricant demand of your point. The per-stroke volume is per piston stroke, not per point dose.
What does spring-return mean?
Spring-return means the drive presses the plunger out and the spring returns it to refill. The return stroke is not powered by the drive.
Will it fit my pump housing?
The M20x1.5 thread fits a matching port, but thread alone does not guarantee fit. Confirm piston diameter, stroke, and drive geometry before ordering.
What lubricants can it handle?
It handles grease up to NLGI 2 and oil viscosity up to 40 cSt. Stay within these limits for reliable spring return.
What does the relief valve do?
An integrated relief valve is available on select models to limit pressure in the element circuit. It helps protect the element and downstream components from overpressure.
How is it installed?
Screw the element into the M20x1.5 port and torque to 25-30 Nm. Do not apply sealing compounds on the lubricant path.
Does the thread seal the lubricant path?
The thread provides mechanical retention, but the sealing is handled by the element seals. The threaded body must seat correctly in the housing.
How do I order the right M20x1.5 element for my pump?
IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006, builds and supports every unit. Email inquiry@isohitech.com for specifications and a quotation.
Confirm your thread, piston diameter, stroke, and delivery rate, then request a quote through the contact page.
