Threaded Eye Ends for Cylinders & Linkage

Rod Eyes — Threaded Eye Ends

Q: What does RER vs REL mean?

RER is the right-hand thread rod eye; REL is left-hand, used together for adjustable assemblies.

Q: What material are rod eyes?

The catalog lists zinc-plated carbon steel. Confirm the manufacturing process and required finish on the drawing or quote.

Q: What sizes are available?

Bore 1/2 inch to 3/4 inch, thread 1/2-20 to 3/4-16, across 6 standard sizes.

A rod eye is a solid eye end with a threaded shank — a simple, rugged pivot point for cylinders, springs, shocks and linkage, without a spherical bearing. SYZ rod eyes are zinc-plated carbon steel in right-hand (RER) and left-hand (REL) thread: bore 1/2″–3/4″, thread 1/2-20 to 3/4-16, 6 sizes.

Browse Rod Eye Sizes ↓ Request a Bulk Quote

6 sizes

RER / REL pairs

Carbon steel

Zinc plated

RER + REL

RH / LH thread

1/2″–3/4″ bore

1/2-20 to 3/4-16

ISO 9001:2015 Quality

Overview

What Is a Rod Eye?

A rod eye (eye end) is a one-piece fitting with a circular eye (for a pin/bolt) and an integral threaded shank. Unlike a rod end, it has no spherical bearing — it provides a simple single-axis pivot. It’s the economical choice for cylinder rods, spring/shock mounts and basic linkage where multi-axis articulation isn’t needed.

RH & LH Pairing

RER and REL let you keep right-hand and left-hand thread logic consistent with the rest of the linkage, especially when matching rod ends or spring hardware.

6 Standard Sizes

Rod Eye Size & Dimension Table

Open Interactive Spec Selection →

Choose the eye bore for the pin first, then match the RER/REL thread to the rod. D is the eye outside diameter, W is eye width, and A/C are the published length dimensions.

Part no. pair	Bore	Thread	D	W	A	C
RER8 / REL8	0.500″	1/2-20	1.312″	0.625″	2.437″	1.500″
RER8-12 / REL8-12	0.500″	3/4-16	1.500″	0.875″	2.875″	1.750″
RER10 / REL10	0.625″	5/8-18	1.500″	0.750″	2.625″	1.625″
RER10-12 / REL10-12	0.625″	3/4-16	1.500″	0.875″	2.500″	1.650″
RER10-12-1 / REL10-12-1	0.625″	3/4-16	1.750″	0.875″	2.875″	1.750″
RER12 / REL12	0.750″	3/4-16	1.750″	0.875″	2.875″	1.750″

Engineering Guide

Selection Guide

Single-Axis or Multi-Axis?

Need a simple single-axis pivot with no articulation → rod eye; need multi-axis / misalignment capability → use a rod end instead.

Pick Thread Hand

Pick RER (right-hand thread) or REL (left-hand thread) to match your rod or adjuster. Use RER + REL together for adjustable-length assemblies.

Match Thread & Eye Bore

Match thread to the rod and bore to the pin/bolt for a close fit; confirm eye dimensions and pin shear on the spec page.

Industrial Uses

Applications

Hydraulic/pneumatic cylinder rod ends, spring and shock mounts, simple control linkage, and machinery pivots that hinge on one axis.

Hydraulic & Pneumatic Cylinders

Cylinder rod end fittings where the eye attaches to a pin and the shank threads onto the cylinder rod — single-axis pivoting under load.

Most common application

Spring & Shock Mounts

Attaching springs or shock absorbers at a single pivot point where no angular misalignment compensation is needed.

Suspension & linkage

Simple Control Linkage

Basic machinery control linkages, actuator connections and control rod ends that hinge cleanly on one axis without misalignment.

Machinery & agricultural

Machinery Pivots

Single-axis machinery pivots and pin joints where a solid threaded eye end fits the load path.

Industrial equipment

Technical Guide

Rod Eye vs Rod End vs Clevis — Choosing the Simplest Joint That Works

A rod eye is the most basic of the three pivot fittings — and often the right answer when designers over-spec a spherical rod end out of habit:

	Articulation	Construction	Choose when
Rod eye	Single-axis pivot, no bearing	One-piece eye + threaded shank	The joint hinges on one pin axis; no misalignment needed
Clevis / yoke	Single-axis hinge	Fork + cross pin	Same single-plane motion but you want a fork-and-pin interface
Rod end (heim joint)	Multi-axis (spherical)	Ball-in-housing + thread	The joint must tilt out of plane / absorb misalignment
Hydraulic cylinder rod end	Single-axis eye with spherical bearing	Bearing in eye housing + threaded rod connection	The cylinder eye needs bearing articulation; confirm the hydraulic series

Because it has no spherical bearing to wear, a rod eye is rugged, economical and maintenance-light — ideal for cylinder rods, spring/shock eyes and basic linkage. The trade-off is zero misalignment capability: if the mating geometry tilts off-axis, the pin binds and you need a rod end instead.

Fitting checklist: match the thread (and hand — RER right-hand, REL left-hand for adjustable pairs) to the rod; match the eye bore to the pin/bolt for a close fit; confirm the eye dimensions and pin shear on the spec page; lock adjustable assemblies with a jam nut.

Engineering Detail

Sizing & Failure Modes

Two dimensions drive a rod eye selection: the thread (to the rod) and the eye bore (to the pin). Get either wrong and the joint either won’t fit or wears fast.

Symptom	Cause	Prevention
Pin bore wallows / elongates	Bore too large for pin (slop)	Match bore to a close fit on the pin/bolt
Eye cracks at the neck	Side/bending load on a single-axis joint, or undersized	A rod eye is single-axis only — use a rod end where the joint tilts off-plane; size up if loaded hard
Thread strips	Insufficient engagement	Keep full thread engagement at the set length
Surface rust	Plating worn / wrong environment	Re-coat, or specify a corrosion-resistant option for wet/outdoor use

Single-axis only — the key limit: Check pin shear capacity before finalizing the joint. A rod eye has no spherical bearing, so it only pivots on its pin axis. If your geometry imposes any out-of-plane angle, the pin binds and the eye is loaded in bending — that’s when you move to a rod end or, for a fork interface, a clevis.

Complete the Link

Choose the Next Joint Component

Clevis Rod Ends

Use a G-series clevis when the pinned fork interface is the better fit.

Jam Nuts

Lock RER/REL threaded assemblies after the length is set.

HCR20U hydraulic cylinder rod end bearing

Hydraulic Cylinder Rod Ends

Upgrade to the spherical-bearing hydraulic rod-end family when the cylinder eye needs articulation.

Rod ends and heim joints parent hub group shot

Rod Ends / Heim Joints

Choose a spherical rod end when the linkage must absorb multi-axis misalignment.

FAQ

Common Questions

What’s the difference between a rod eye and a rod end?

A rod eye is a solid eye with a threaded shank and no bearing — a simple single-axis pivot. A rod end has a spherical bearing for multi-axis articulation.

What does RER vs REL mean?

RER is the right-hand thread rod eye; REL is left-hand — used together for adjustable assemblies.

What material are rod eyes?

Carbon steel, zinc plated. Confirm the manufacturing process on the drawing or quote.

What sizes are available?

Bore 1/2″–3/4″, thread 1/2-20 to 3/4-16, 6 sizes — see the spec page for D, W, A and C dimensions.

Can a rod eye replace a rod end?

Only where the joint moves on a single axis; if the linkage needs angular misalignment, use a rod end.

Engineering Tools

Calculators for This Product Family

Bolt Shear Capacity Calculator

Estimate single- and double-shear capacity for a pin or bolt.

Bolt Preload & Torque Calculator

Estimate tightening torque for bolted joint hardware.

Buyer Guides

Buyer Guides for This Product Family

Rod Eyes

Factory Direct

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