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This guide collects the specification and buying detail behind our truck & commercial vehicle components catalogue. For wholesale quotations, browse the catalogue, send part numbers through a parts list upload or request product sourcing for items that are not listed online.
What this category covers
- Steering: king pin kits for beam front axles, along with tie rod and drag link parts in the steering categories.
- Air brakes: air brake components including valves, chambers, slack adjusters and air dryers.
- Air supply: air compressors and repair kits.
- Suspension: spring pins, shackles and bushings for leaf-sprung axles.
- Cabin: cab tilt pumps and cylinders, cab mounts, mirrors, handles and steps.
- Lighting: 24V lamps and LED lighting for trucks and trailers.
- Sealing: hub, axle and engine oil seals and O-ring kits.
Vehicles and systems
Trucks such as the Hino 500 series, Isuzu NPR and wider N- and F-series, Mitsubishi Fuso Canter and Fighter, and UD trucks share common system types but use model-specific components. Light trucks typically use hydraulic brakes, sometimes with air or vacuum assistance, while medium- and heavy-duty trucks may use air-over-hydraulic or full air brakes depending on class and market. Most use leaf-sprung beam axles with king pins, and many use 24V electrical systems.
Wear drivers
- Overloading, which accelerates wear of king pins, spring pins, bushings and brakes
- Unpaved roads and construction sites introducing dust and impacts
- Irregular greasing of king pins, spring pins and slack adjusters
- Water and contamination in air brake systems when air dryers are not maintained
- Heat and long descents that stress brakes and seals
Identification
Truck parts should be specified by chassis model and variant, axle model, engine code where relevant, and the OEM part number. Many truck components are also marked with manufacturer references that help cross-reference when OEM numbers are unavailable. Photos and measurements help with older trucks.
Fleet-oriented supply
Truck operators measure parts supply by uptime. A truck waiting for a king pin kit or a relay valve earns nothing, so fleet customers value distributors who stock complete kits for their chassis and can supply related items in one order. Building stock around the actual chassis and axle mix of key fleet customers, rather than broad catalogue coverage, typically gives better availability for the same inventory investment.
See the truck parts section for model-based ranges, and submit parts lists via RFQ upload.
Buying and specification checklist
Specification essentials
- Chassis model and variant, year and market, since trucks are built in many configurations.
- Axle model for king pins, brakes, hubs and seals.
- OEM number and any stamped component reference.
- Brake system type: hydraulic, air-over-hydraulic or full air.
- Voltage: 12V or 24V for electrical parts and lighting.
Kits and completeness
Fleet workshops value complete kits because trucks off the road cost money. King pin kits should include pins, bushes, thrust bearings, shims and seals; air brake repair kits should include all seals and diaphragms for the valve; spring pin kits should include pins, bushes and grease nipples.
Quality checks
- Hardness and surface finish of king pins and spring pins
- Bushing material (bronze or composite) and dimensions
- Rubber compounds in diaphragms and seals suitable for heat and oil
- Thread and port quality on air valves
- E-marking or local approval marks for lighting where required
Packaging
Truck components are heavy for their size. Use strong cartons, protect machined surfaces with oil or VCI packaging, and cap air valve ports to keep dirt out.
Consolidation
Truck components combine well with truck filters, brake linings and bearings in a mixed container, particularly for fleet customers who order by chassis model.
Documentation
Provide packing lists that group items by chassis model and include OEM numbers. This speeds customs clearance and receiving, and helps fleet workshops confirm that a consignment covers their planned maintenance.
Product types in detail
King Pin Kits
King pins connect the steering knuckles to the front beam axle on most trucks and many older 4x4s and light commercial vehicles. They carry the vehicle's front axle load while allowing the wheels to steer. Worn king pins and bushings cause steering wander, shimmy, uneven tire wear and poor braking stability. Browse king pin kits in the catalogue.
Typical kit contents
- King pins – hardened steel pins, sometimes chrome-plated, with grooves or flats for draw keys or lock bolts.
- Bushings – bronze bushes, steel-backed composite bushes, or needle roller bearings on some axles.
- Thrust bearings – tapered roller or ball thrust bearings, or thrust washers, carrying vertical load between knuckle and axle.
- Shims – to set vertical clearance.
- Seals and O-rings – to retain grease and exclude dirt.
- Draw keys, cotter pins or lock bolts, caps and gaskets.
- Grease nipples for regular lubrication.
Kit contents vary by supplier, so each component must be confirmed.
Installation considerations
Bronze bushings are often pressed into the knuckle and then reamed or honed to final size, which requires tooling and skill. Some kits supply pre-sized bushes that do not require reaming. Correct thrust bearing orientation, shim selection and greasing after installation are essential.
Failure drivers
Irregular greasing, overloading, dust and water from unpaved roads, and worn thrust bearings. Fleets that grease king pins at every service see much longer life.
Applications
King pin kits are specific to the front axle model on trucks such as the Hino 500 and Isuzu NPR. The same chassis may use different axles depending on GVW. Related parts: tie rod ends.
Ordering checklist
- Chassis model, axle model and OEM kit number, plus axle markings where available.
- Pin dimensions: diameter and length, groove or flat positions.
- Bushing type: bronze requiring reaming, pre-sized bushes, composite or needle bearings.
- Thrust bearing type: tapered roller, ball or washer.
- Kit contents list: pins, bushes, bearings, shims, seals, keys, caps and nipples. Kits typically cover both sides of one axle, but confirm.
- Material quality: pin hardness and surface finish; bushing alloy.
- Packaging: oiled or VCI-wrapped pins, separated components, labeled bags for small parts.
- Tooling: consider stocking reamers or offering guidance for bronze bush installation.
- Fleet demand: order by the axle types most common in the local fleet; heavy use justifies deeper stock.
- Oversize options: some axles accept oversize king pins after worn knuckle or axle bores are machined. Ask whether oversize kits exist for the main axle references.
- Related parts: stock tie rod ends, drag link ends and hub seals for the same axles, since king pin jobs often expose other front-end wear.
Air Brake Components
Air brake systems use compressed air to apply brakes on medium- and heavy-duty trucks, buses and trailers. They are robust but depend on clean, dry air and regular maintenance, and failed valves or chambers directly affect braking safety. Browse air brake components in the catalogue.
Air supply and treatment
- Air compressor and governor or unloader – see air compressors.
- Air dryer and desiccant cartridge – removes moisture and oil before air enters the tanks.
- Reservoirs and drain valves – store air and collect condensation.
- Protection valves – multi-circuit protection valves separate brake circuits.
Control valves
- Foot brake valve (dual brake valve) – controls service brake air pressure to front and rear circuits.
- Relay valves – speed up application and release at the rear axles.
- Quick release valves – exhaust air quickly from front chambers.
- Hand control and parking valves – operate spring brakes and trailer brakes.
Foundation brake actuation
- Service brake chambers – identified by type numbers such as 16, 20, 24 or 30, which relate to the effective diaphragm area in square inches.
- Spring brake chambers – combine a service chamber with a powerful spring for parking and emergency braking, identified by combinations such as 24/24 or 30/30.
- Slack adjusters – manual or automatic, specified by spline count, arm length and cam shaft diameter.
- Wedge brake actuators on some truck axles.
Air-over-hydraulic systems
Some Japanese medium trucks use an air master (air-hydraulic booster) that converts air pressure into hydraulic pressure for wheel cylinders. These boosters and their repair kits are a distinct part group.
Maintenance and failure drivers
Moisture in the system causes valve corrosion and freezing in cold climates; oil carryover from worn compressors damages diaphragms and seals. Neglected air dryer cartridges are a frequent root cause. Trucks such as the Hino 500 should be checked for system type before ordering. See truck brake parts for linings and drums.
Ordering checklist
- Chassis model, brake system type and axle position.
- OEM number or manufacturer reference stamped on valves and chambers.
- Chambers: type size, stroke length, pushrod length and clevis, mounting stud spacing, port positions.
- Slack adjusters: manual or automatic, spline count, arm length, shaft diameter and left or right orientation.
- Valves: port count, thread sizes and function; confirm whether repair kits are available.
- Repair kits: diaphragms, seals and springs by valve reference.
- Air dryer cartridges: thread size, seal diameter and whether oil-coalescing.
- Packaging: cap all ports and protect threads; chambers are heavy and should be boxed individually.
- Quality: rubber compounds for heat and oil resistance; valve body casting quality.
- Safety: spring brake chambers contain high spring force and must never be disassembled without proper tools and procedures. Include warnings with the product.
- Maintenance kits: air dryer cartridges and valve repair kits are recurring items; stock them in proportion to the trucks in your customers' fleets.