The duty of PHS Series Maintenance-Free Rod Ends is putting a spherical sliding joint on the end of a threaded body, so a linkage can be bolted up, articulated and adjusted for length without machining a housing bore. The same spherical sliding element as a plain bearing, carried in a body with a male or female thread: the joint articulates and the thread lets the linkage be adjusted and locked with a jam nut. The sections that follow cover the sectors that specify them, how to state the designation, clearance, sealing, cage and fit on an order, how to mount them, and the known limits of the type. Dimensions are to Manufacturer series to DIN ISO 12240-4 envelope. This series is catalogued from 5 mm to 20 mm bore; the full table of boundary dimensions is further down the page.
Typical Applications for PHS Series Maintenance-Free Rod Ends
The machine positions and sectors where this type is specified:
- Cylinder and actuator ends: the pivot at the rod end of a pneumatic or hydraulic cylinder.
- Motorsport and specialist suspension: adjustable links where geometry is set by turning the rod end on its thread.
- Agricultural machinery: implement linkages and adjustable stays exposed to shock and to weather.
- Aerospace and marine controls: push-pull control rods where a defined misalignment capability is part of the design.
- Maintenance and repair (MRO): replacing a failed bearing where the original designation, clearance group and sealing have to be matched exactly.
How to Specify PHS Series Maintenance-Free Rod Ends for Your Application
- Bore: Start from the bore the shaft or housing gives you — this series is catalogued from 5 mm to 20 mm — then check the outer diameter and width against the space available. The boundary dimensions are fixed by the standard, so they are the same from any manufacturer; the load ratings and limiting speeds are not, and belong to the specific bearing being supplied.
- Thread hand and jam nut: State the thread size, form and hand, and allow for a jam nut. Adjustable links use one right-hand and one left-hand end so the length can be set without disconnecting the joint.
- Thread size and hand: State the thread, the form and the hand. A left-hand rod end at one end of a link and a right-hand one at the other is what allows the length to be adjusted by turning the tube without disconnecting either end — and the two are not interchangeable.
- Male or female body: A male rod end (SA, PHS) screws into a tapped hole or a tube insert; a female rod end (SI, PHSB) receives a threaded rod. That decision constrains the rest of the linkage, so it belongs on the drawing.
- Liner and load: Steel-on-steel with a lubrication hole carries more and needs greasing; a PTFE liner runs maintenance-free with a lower rating. Rate the joint on static load and on the misalignment angle it must reach at the extremes of travel.
- Designation and suffixes: State the complete designation including every suffix. The base number gives the type and the boundary dimensions; the suffixes carry the sealing, the cage, the clearance group, the tolerance class and any special execution — and two bearings whose base numbers match but whose suffixes differ are not interchangeable.
- Clearance and tolerance: State the running clearance or fit class the assembly requires, together with the tolerances of the mating parts that produce it. For this type the clearance is created by the parts around the bearing rather than being built into it, which is precisely why it has to be written down.
- Sealing arrangement: This type is supplied open, so the sealing belongs to the housing around it. Specify the shaft seal, flinger or labyrinth that will keep the lubricant in and contamination out — with an open bearing, the sealing arrangement, not the bearing, decides how long it survives its environment.
- Cage: not applicable: This part has no cage and no rolling elements to separate, so the equivalent decision is the sliding material or liner. That is stated above, and it plays the same role: it is what sets the temperature limit and the lubrication requirement.
- Shaft and housing fit: Specify the seat tolerances, not just the bearing. The rule is that the ring which rotates relative to the load direction takes the interference fit: for a rotating inner ring under normal radial load the shaft seat is typically k5 or k6 with the housing bore H7, and where the outer ring rotates the interference moves to the housing (N7 or P7) with a clearance fit (g6) on the shaft. Heavier loads and hollow shafts move the fits tighter. A correctly chosen bearing in the wrong fit fails anyway — too loose and the ring creeps and frets its seat, too tight and the interference consumes the internal clearance and the bearing runs preloaded.
- Standard: Boundary dimensions are to Manufacturer series to DIN ISO 12240-4 envelope. Quoting the standard on the order guarantees the mounting dimensions are interchangeable between suppliers — it does not standardize load ratings, limiting speeds or internal design, which remain manufacturer-specific.
Mounting & Assembly Practice
- Screw the rod end in to at least the minimum thread engagement stated for the size — usually one and a half times the thread diameter — and lock it with a jam nut against the body.
- Clamp the ball between the fork faces so the bolt is in double shear and not in bending. A bolt taking the load in bending will fail long before the bearing does.
- Check the articulation angle through the full travel of the mechanism, not just at the neutral position.
- Keep the load along the shank axis. A rod end is a tension and compression member; side load applied to the head is carried in bending by the body.
Common Selection Mistakes with PHS Series Maintenance-Free Rod Ends
- Not enough thread engagement, so the load is carried by two or three threads in the shank.
- Running the linkage past the permissible misalignment angle at the end of travel, where the ball shoulder contacts the housing edge and the joint is loaded on an edge instead of a spherical surface.
- Using a rod end where the joint is really a rotating bearing — the sliding contact wears rapidly under continuous rotation.
- Sizing this bearing from the boundary dimensions alone. Load ratings and limiting speeds are manufacturer-specific for this series and are deliberately not published here — take them from the catalog of the bearing actually being supplied and calculate the life against them.
Where PHS Series Maintenance-Free Rod Ends Are Not the Right Choice
- Not for continuous rotation; this is an oscillating sliding joint.
- Not for loads applied across the head. The body is designed for tension and compression along the shank, and side load puts it in bending.
- Not where the misalignment exceeds the catalog angle for the series — beyond it the ball contacts the housing edge.
- Not a substitute for a hinge or a pivot bearing that carries a moment.
- The alignment capability is for a static angle between the shaft and the housing seat; it is not a licence to leave a shaft line unaligned, and it does not absorb misalignment that changes every revolution.
