A zerk fitting, also known as a grease fitting, is a small component that provides an entry point for lubricant into equipment that needs regular greasing. It consists of a small metal cylinder with threads on the outside to screw into a grease port, and a spring-loaded check valve on the inner end.

Purpose

The purpose of a zerk fitting is to allow lubricant, typically grease, to be pumped into parts of machinery that require routine lubrication, like bearings, bushings, pivots and other friction points. This helps reduce wear and prevents overheating or binding.

Types

Common types of zerk fittings include straight, 45 degree angle, 90 degree angle, and specialty heads to fit space constraints. The internal check valve style also varies, with some designed for high pressure or to release trapped air. Materials range from basic steel to hardened stainless steel for long life.

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When to Install a Zerk Fitting?

New Equipment

Installing zerk fittings on new equipment or machines enables routine access to lubrication points. Grease ports should be added wherever the manufacturer specifies, which is typically where lubrication is required for bearings, shafts, hinges or other movable parts. Adding extra fittings allows for tuning lubricant amounts.

Replacing Damaged Fittings

Over time, fittings may become clogged or leak due to seal wear or damage. Replacing worn zerks maintains lubrication access to keep parts properly greased. This prevents premature wear leading to costly repairs or replacement.

Improving Lubrication Access

Adding a zerk where none existed can optimize a lubrication routine. Strategically placing extra zerks delivers grease deeper into friction zones. Correct lubricant amounts and frequency becomes customizable.

Preparing to Install a Zerk Fitting

Gather Tools and Materials

Typical tools:

• Drill and drill bits for metal
• Tap handle and tap for zerk threads
• Wrench for turning fitting
• Grease gun
• Degreaser/cleaner
• Safety glasses

Materials:

• Zerk fittings
• Thread sealant
• Grease

Select Fitting Type and Location

Assess lubrication needs and accessibility limitations to determine fitting types, locations and the optimum number to install. Consider equipment use, maintenance schedule, environment and space constraints.

Clean Mounting Surface

Degrease and clean the equipment area thoroughly where fittings will be installed to allow sealant and grease to adhere properly. Remove all debris, dirt and grime from lubrication ports.

Installing a Zerk Fitting

Drill Hole

Determine Hole Size

Refer to zerk packaging for appropriate drill hole size, typically between 1⁄4 to 1⁄2 inch depending on fitting type. Larger is preferable to allow space for sufficiently pumping grease.

Use Bit for Metal

Slowly drill a straight, clean hole using a bit designed for metal at the marked location, perpendicular to the lubrication port surface.

Insert Fitting

Impact or Press Method

Use an arbor press or mallet to fully impact the zerk threads into the freshly drilled hole. Avoid over-tightening.

Thread Sealant

Apply thread sealant onto zerk threads beforehand for a leak-free tight seal since machine vibrations can gradually loosen fittings over time.

Attach Hose or Grease Gun

Screw in the grease gun tip tightly once inserted to prevent grease backflow under pressure. Flexible hoses also stay thread-sealed and allow for routine lubrication access if required for hard-to-reach locations.

First Time Greasing

Confirm Smooth Piston Movement

Check that the zerk fitting’s internal check valve piston slides easily when pressed before attaching grease gun. Bent or jammed check valves indicate fitting damage or blockage.

Pump Grease Until Clean Extrusion

During initial greasing after new zerks are installed, continuously pump the lever of the grease gun until fresh, uncontaminated grease visibly extrudes from the lubrication point. This fills the void fully.

Proper Maintenance

Routine Lubrication Schedule

Establish and follow a lubrication routine based on environment and use. Greasing intervals vary between weekly and 2-3 times annually. Periodically check that grease is reaching the friction zone.

Inspect for Leaks/Damage

Routinely examine zerk fittings and lubrication points to check for blocked passages causing asymmetric bulging or grease leaks indicating damage requiring immediate replacement.

Troubleshooting Installations

Leaks

If leaks occur, thoroughly clean the fitting and port then re-seal threads with fresh tape sealant before reinstalling. Consider switching to a higher quality zerk fitting if issues persist.

Blocked Passages

Improperly sized holes or damaged fittings block internal piston check valves. Refit or redrill the port then blast compressed air into the grease passageway to remove debris before replacing the zerk.

Safety Tips

Use Eye Protection

Drilling and impacting fitting hardware pose eye injury risks from flying fragments or debris. Always wear safety glasses.

Allow Equipment to Cool

If recently operating, let machinery cool fully before attempting installation near hot lubrication ports to prevent burns.

Benefits of Proper Lubrication

Extended Component Life

Routine greasing via zerk fittings dramatically extends the usable life of wear parts like bearings, bushings and pivots by preventing excessive friction when moving.

Reduced Wear and Repairs

Adequate lubrication enabled by grease zerks minimizes abrasive wear between components, reducing the need for repairs or replacements and associated costs.

Reliable Operation

Maintaining proper lubrication keeps parts from binding or seizing, enabling reliable function for consistent operation and production.

Alternative Lubrication Methods

Oil Ports

Components with space constraints restricting zerks usage can alternatively utilize small push-pull oil ports for introducing oil internally, typically via automated centralized systems instead of manual greasing.

Centralized Systems

Centralized automated lubrication systems constantly deliver regulated oil or grease amounts to multiple equipment zerks or ports simultaneously without manual intervention.

FAQs

What size hole do I drill for a standard zerk fitting?
For most standard 1/4” or 3/8” zerk fittings, a hole sized between 1/4 and 3/8 inches is ideal depending on lubrication requirements. Larger holes allow more pumped grease to penetrate deeply.

Should I use Teflon tape on zerk fittings?
Yes, wrapping zerk threads with 1-2 layers of Teflon tape before installation promotes a superior leak-free seal and helps prevent vibrational loosening over long-term equipment operation.

How often should grease fittings be lubricated?
Greasing frequency varies based on bearing type, rotation speeds and operating environment. Most equipment needs greasing weekly to quarterly, while some heavy machinery requires daily lubrication via grease zerks.

Can I install a zerk fitting myself?
With common tools, adding grease zerks is a straightforward DIY project if manufacturer installation guidelines covering proper positioning and hole sizing are available. Ensure robust seals using thread sealant.