Southern States EV2 Linkage Arm Rebuild & Upgrade
The EV2 linkage arm connects the operating mechanism to the switch blade. The OEM design uses dissimilar metal combinations at three different points — aluminum against steel at the ball joint nut, steel set screws prone to seizing in place, and a steel shaft running directly in an aluminum bore at the pivot. Each one is a future maintenance problem. We rebuild the arm with stainless and brass hardware throughout and eliminate all three.
Three seize points
in a single casting.
The EV2 linkage arm is a zinc-alloy casting that sees weather, vibration, and decades of thermal cycling. The OEM chose soft aluminum for the ball joint nut and relied on Allen-key set screws for adjustment locking. Both choices produce the same outcome: hardware that corrodes into place and can't be serviced without destruction. The pivot bore is bare aluminum — when the steel shaft corrodes, it migrates into the bore and binds.
OEM uses a soft aluminum nut with a flat for a standard screwdriver. Aluminum against the steel ball joint corrodes and welds the nut in place. Adjustment becomes impossible; removal requires destruction of the nut.
OEM uses steel Allen-key set screws to lock the adjustment. These seize in the casting threads. The small Allen socket is the first thing to strip, leaving no purchase. Getting them out without damaging the arm is difficult work.
The pivot end runs a steel shaft directly in an aluminum bore. Galvanic corrosion works from the shaft outward into the bore. The shaft seizes in the arm, and the bore material degrades until it can't hold a shaft reliably.
Same casting.
Different hardware.
The zinc casting itself is sound — it doesn't corrode under normal service. We reuse it. Every piece of hardware that touches a dissimilar metal gets replaced. The result is an arm with no galvanic couples and hardware you can still turn with a wrench after twenty years in the field.
The OEM steel ball joint and aluminum nut are replaced with a stainless ball joint and a machined brass nut. The brass nut has a full ¾″ hex head — a standard wrench, not a screwdriver slot. It can be adjusted and removed in the field with a box end. The stainless-to-brass contact has no galvanic couple that would corrode them together.
- →Stainless steel ball joint replaces OEM steel
- →Brass nut with ¾″ hex replaces aluminum nut with screwdriver flat
- →No galvanic couple between mating parts
- →Loctite applied at assembly; nut remains removable
The OEM steel Allen-key set screws are replaced with brass set screws with hex heads. Brass doesn't corrode against the zinc casting. The hex head gives you a real wrench purchase — not a small Allen socket that's the first thing to round off when you're fighting a seized fastener on a pole.
- →Brass set screws replace OEM steel Allen-key type
- →Hex head provides wrench access in the field
- →Brass-to-zinc contact will not corrode together
The aluminum pivot bores are machined out and brass bushings are pressed in. The steel OEM shaft is replaced with a stainless shaft. Brass against stainless is a compatible material pair with no galvanic seize potential. The brass bushing also protects the casting bore — if the bushing ever needs replacement, the arm itself is undamaged.
- →Pivot bores machined and fitted with pressed brass bushings
- →OEM steel shaft replaced with stainless
- →Brass-to-stainless: no galvanic couple
- →Bushing is the wear surface — casting bore is protected
The bearing and the linkage arm fail for exactly the same reason: the OEM put dissimilar metals in direct contact in an outdoor environment and expected them to last the life of the structure. We do the same refurbishment on both — remove the galvanic couples, replace with compatible metals. The casting stays; the hardware that corrodes gets replaced. See the EV2 bearing refurbishment →
Send us your arms and we’ll rebuild them with stainless and brass hardware. Ready to reinstall. Call (727) 789-0951 or request a quote.