30/30 Spring Brake Chamber

Spring brake chambers in the 30/30 family

Combination spring brake chambers merge service diaphragm action with parking spring force in one housing. The MGM 30/30 type listed here is a common footprint on tractors where space and plumbing favor a standard spring brake chamber body. Failures appear as audible air leaks, weak parking hold, or pushrods that no longer move through full stroke.

Chamber replacement is high consequence work. Spring energy stored in the parking section can injure technicians who skip caging steps. Treat every chamber swap as a formal spring brake procedure, not a quick air line change.

This listing is for a spring brake chamber in the 30/30 category referenced on the product card. Pushrods, slack adjusters, and mounting hardware may reuse only if inspection passes.

Published make coverage

Fitment examples name Freightliner, Kenworth, Mack, and Peterbilt tractors with All engine rows in the table. Vocational upfits sometimes relocate chambers or use different clevis lengths within the same model name.

Verify using stamp photos, VIN build data, and pushrod length measurements. The fitment guide helps when you maintain both tractors and matching trailers.

Contact support@aonetruckauto.com with cage tool photos if you are unsure whether a unit uses standard or deep-stroke caps.

Weight and price on the card

Ship weight is 18.0 lb. Price is $74.90 USD before tax. Use weight for freight planning, not as a substitute for chamber stroke ratings printed by the maker.

Shipping classes and return windows are on the shipping policy and returns and refunds pages.

Caging and uncaging discipline

Before loosening chamber bolts, install the correct caging tool and verify spring compression per the chamber label. Never rely on air pressure alone to hold a parking spring during removal.

After install, release the cage only when clevis pin, pushrod, and slack adjuster alignment are confirmed. A misaligned rod bends pushrods and destroys new diaphragms quickly.

Post-install checks

• Leak-down test service and parking sections separately where procedure allows.
• Measure pushrod stroke after adjuster setup and compare to axle limits.
• Apply and release parking brake repeatedly at low pressure to confirm hold.
• Document cage tool serial or rental tag on the work order for liability records.

Keep removed chambers until stamps are photographed for core or credit paperwork your fleet requires internally.

Ordering clarity

Match the 30/30 designation to the tag on the old body and confirm port orientation before checkout. PayPal capture on this site completes only after payment succeeds.

Plumbing and port orientation on chambers

Spring brake chambers fail early when ports are stressed by hard lines pulled into alignment. Support lines so vibration does not transfer into the diaphragm crimp. Replace crushed fittings instead of forcing thread sealant to compensate for oval ports.

Parking spring tension that feels weak after install may be a mis-set pushrod length rather than a defective chamber. Measure rod stroke against the data sheet for that chamber family before you RMA good parts.

Combination vehicles need consistent chamber sizes across matched axles when ABS modulation expects balanced timing. Document any intentional mismatch approved by engineering.

Air line inspection pairing

• Replace brittle nylon sections upstream of the chamber when found during service.
• Confirm glad hand seals at the tractor do not leak before chamber stroke tests.
• Verify modulator airlines are labeled if multiple chambers share a rail.
• Log chamber stamp and pushrod length together on close-out.

Air plumbing photos help later crews when a different technician chases the same unit number.

Spring brake safety culture

Shop leads should verify cage tools are present before assigning chamber R&R on spring brake axles. Borrowed tools without calibration records create liability when something slips. Tag-out procedures for units on lifts prevent accidental air apply during clevis work.

Drivers need a short briefing after chamber work so they know parking brake feel may differ until break-in cycles complete. A softer initial feel is not always a defect if stroke checks passed.

Brake balance after chamber replacement

After spring brake service, road test includes a controlled stop from moderate speed feeling for pull. Pull may indicate plumbing reversed or adjuster stroke unequal side to side. Balance issues belong to the same work order until resolved.

Fleets running lift axles need explicit procedures for caging when only one side of a tandem is lifted. Document training for new hires before assigning chamber work solo.

Caging and pushrod length on 30/30 cans

Type 30/30 chambers need correct caging during service so spring energy cannot injure a technician. Follow the cage-bolt procedure in the chamber maker chart before you crack mounting nuts.

Pushrod length and mounting stud pattern must match the tag on the removed can. A chamber that “almost” fits will bind the slack adjuster and grow stroke on the first grade.

Photograph airline routing before removal so a different technician can chase the same unit without guessing which hose feeds service versus spring brake.

Packaging and carrier options are described on the shipping policy. Return eligibility is on returns and refunds. Questions: support@aonetruckauto.com.

HEAVY TRUCK PARTS, INC. operates A-One Truck Auto. Truck and brand names here describe compatibility only; we are an independent seller.