Brake Chamber 47850-3381 RH 478504171 LH for Japanese Truck

Brake chamber set: RH 47850-3381 (right hand) and LH 478504171 (left hand) for Japanese trucks. Spring brake type with service and parking brake functions. Direct OE replacement for rear axle. No mounting hardware or clevis included. Verify pushrod stroke length before ordering.

These brake chambers are pneumatic actuators designed for Japanese medium and heavy duty trucks including Hino, Isuzu, Mitsubishi Fuso, and Nissan Diesel (UD) models. The RH (47850-3381) and LH (478504171) are mirror image pairs for the rear axle. Each chamber combines two functions: the service brake section (primary) and the parking/emergency spring brake section (secondary).

The chamber housing is constructed from heavy gauge steel with a corrosion resistant e‑coat finish. A clamp ring seals the two housing halves together with a diaphragm inside. The pushrod extends from the service brake side. An internal power spring (compressed) provides parking brake force. Releasing the parking brake requires applying air pressure to compress the spring.

These chambers are typically type 30/30 or similar, indicating the effective area in square inches. The pushrod stroke is approximately 75‑100 mm (3‑4 inches) depending on the exact specification. The pushrod end has a clevis or yoke with a cotter pin hole.

This replacement set is suitable when original chambers show signs of rust perforation, diaphragm leakage (causing slow brake release), power spring failure (parking brake does not hold), or pushrod corrosion. Replace both chambers on the same axle simultaneously for balanced braking.

Installation notes: Before removing old chambers, cage the parking brake spring using the caging bolt to release spring tension. This is mandatory for safety. Mark air lines to identify service and parking ports (typically two lines per chamber). Remove old chamber. Clean mounting bracket surface. Install new chamber with new lock washers. Torque mounting nuts to 100‑120 Nm. Connect air lines finger tight then tighten 1/4 turn. Test for leaks with soapy water. Adjust pushrod stroke to manufacturer specification (usually 40‑50 mm at 4‑5 bar application). Re‑check after road test.

Matching pairs: The RH and LH chambers are not interchangeable. The left chamber has its pushrod offset to clear differential housing. Always order the correct side.

Caging bolt note: Each new chamber includes a caging bolt (or reuse original). Keep the bolt accessible for emergency parking brake release.

Q1: Which Japanese trucks use these brake chambers?

A1: These numbers fit many Hino (Ranger, Profia), Isuzu (Forward, Giga), Mitsubishi Fuso (Fighter, Super Great), and UD (Condor, Quon) trucks with rear drum or disc brakes. Verify your original chamber dimensions.

Q2: What is the difference between RH 47850-3381 and LH 478504171?

A2: They are mirror images. The left chamber has the pushrod offset to the right side (when viewed from rear) to clear the differential. The right chamber is straight or offset opposite.

Q3: Do I need to replace both chambers at the same time?

A3: Yes. Replacing only one side creates uneven braking force. The vehicle may pull to one side during hard stops. Always replace as an axle pair.

Q4: How do I know if my brake chamber has failed?

A4: Symptoms include: vehicle fails to hold on parking brake, air leaks from chamber exhaust, brakes drag (slow release), or visible rust through the housing. Also check for pushrod corrosion.

Q5: What is the caging bolt for?

A5: The caging bolt mechanically compresses the power spring inside the chamber. It is used for emergency release of the parking brake when there is no air pressure. Always cage the spring before removing the chamber.

Q6: Can I use these chambers on a trailer?

A6: No. These are designed for truck drive axles with specific pushrod stroke and bracket bolt pattern. Trailer chambers use different dimensions.

Q7: What is the correct pushrod stroke adjustment?

A7: Stroke should be set to 40‑50 mm when 4‑5 bar (60‑70 psi) is applied to the service port. Refer to your vehicle service manual. Excess stroke indicates worn brake linings.

Q8: Are the air port threads metric or NPT?

A8: Japanese trucks commonly use 3/8″ NPT or M12x1.5 metric ports. Check your original chamber. Use appropriate thread sealant for pneumatic connections.