6127115721 / 6127-11-5721 MUFFLER KOMATSU

The 6127115721 / 6127-11-5721 MUFFLER KOMATSU is a heavy-duty exhaust silencer built for large Komatsu equipment, especially D155 and D355 machine families. Public seller listings identify this number as a muffler for Komatsu D155 and D355 applications, while catalog references place the same part inside the exhaust manifold and muffler group for S6D155 engine variants. That combination shows that this part belongs to a serious engine-exhaust system, not to a light accessory category.

From the supplied images, the design matches what buyers expect from a dozer-class exhaust silencer. The body is cylindrical and fully fabricated in steel, with a reinforced side inlet, a broad mounting bracket at the top, and welded transitions that look intended to handle vibration and temperature cycling. The overall construction suggests a part made to support stable exhaust routing, reduce operating noise, and survive long hours in dust, heat, and heavy-load conditions.

At 3GEN Export, we offer this part as an OEM supplier and ship worldwide in 5 working days. For workshops, fleet managers, contractors, and resellers, that matters because an exhaust replacement on a large Komatsu machine is usually tied to active downtime, scheduled maintenance, or a rebuild that needs to move quickly.

Product Overview

Public references are consistent about the basic identity of this component. UCASLAR lists 6127-11-5721 as a muffler assembly in the exhaust category, SSP Machinery lists it as a muffler for Komatsu D155 and D355 machines, and 777parts identifies it as “Muffler” in the exhaust manifold and muffler unit. Those sources align well enough to treat this number as the main muffler or silencer assembly for selected Komatsu heavy equipment powered by the S6D155 platform.

That placement is commercially important because a muffler on a bulldozer or large Komatsu engine does more than soften sound. It is part of the exhaust path that has to handle pressure pulses, hot gas flow, vibration, and support loads from connected pipework. A worn or cracked unit can lead to louder exhaust output, vibration-related stress in the surrounding hardware, and a less stable engine-bay exhaust setup. In real service work, replacing the silencer is often about restoring structural reliability as much as sound control.

For search performance, this product is also valuable because industrial buyers use several kinds of queries. Some search the continuous number 6127115721. Others search the hyphenated number 6127-11-5721. Others search by application, such as Komatsu D155 muffler, D355 muffler, or S6D155 exhaust silencer. A strong product page should support all of those paths naturally, rather than repeating one exact phrase too many times.

What the Images Show

Cylindrical Silencer Body

The large round canister body is the clearest visual clue. This kind of shape is typical in heavy-equipment exhaust silencers because it provides room for internal chambers that reduce sound while keeping the outside profile manageable for installation on the machine. Compared with smaller automotive mufflers, this one looks built for much higher exhaust volume and more demanding duty cycles.

Reinforced Side Inlet

The square side flange with the round opening is a strong indicator of the main exhaust entry point. The reinforced plate around it suggests a bolted or fixed connection area designed to stay rigid under heat and vibration. On a component in this size range, that rigidity matters because the inlet zone takes repeated thermal and mechanical stress.

Heavy Upper Mounting Plate

The upper bracket section includes multiple machined or cast openings and a strong support plate. That tells the buyer this is not meant to hang lightly from a thin strap. It is meant to be mounted securely to the machine so the muffler body and connected pipes are supported correctly during operation.

Welded Industrial Construction

The visible welds and gusseted transitions support the idea of a fabricated steel unit made for long industrial service. That matches the use case of D155 and D355 family machines, where exhaust parts are expected to withstand harsh environments, engine movement, and long-running work cycles.

Where This Part Fits in the Machine

Catalog data places this number in the exhaust manifold and muffler section for S6D155 engine variants, while seller references connect it to large Komatsu dozers. That means the part should be understood as an engine-side exhaust silencer, positioned after the manifold side of the system and intended to manage flow and sound before final discharge. It is not just a decorative shell or a simple connector. It belongs to the core exhaust arrangement of the machine.

In practical field use, that role matters because the engine on a large dozer works under long periods of high load. Exhaust temperatures remain high, vibration is continuous, and the exhaust system is exposed to dust, dirt, and weather. A part in this position needs both thermal endurance and structural strength. If the muffler body or mounting geometry is weak, the surrounding brackets and pipes can end up absorbing extra strain, which raises the chance of repeat repair work.

Compatible KOMATSU Models

Public machine-side listings most clearly support D155 and D355 family usage. SSP Machinery lists the part for Komatsu D155 and D355, while another seller page identifies the same number specifically for D155. Tilly’s lists the product as a muffler for D155A-2, which helps narrow one concrete model-level application inside the broader D155 family.

Based on currently visible public references, the safest model list to present on a product page is:

D155

D155A-2

D355

Engine-side catalog references add another layer of compatibility by linking this number to S6D155 engine variants. Search results from 777parts and IronDT connect 6127-11-5721 with S6D155-4-R, S6D155-4A, S6D155-4AA, S6D155-4B, and S6D155-4S. That is useful because it confirms the engine family behind the machine applications and helps buyers working from engine data instead of machine data.

The engine-family references most commonly associated with this part are:

S6D155-4-R

S6D155-4A

S6D155-4AA

S6D155-4B

S6D155-4S

Because aftermarket listings and catalog pages do not always show the same serial-range detail, the safest buying method is still to confirm machine model, engine family, and serial number before final order approval. That is especially important on older Komatsu machines that may have undergone repairs or exhaust configuration changes over time.

Weight in KG

Published weight references are close but not identical. UCASLAR lists the part at 48 kg, and 777parts search results also show 48.000 kg. A separate 777parts catalog result for the S6D155-4A exhaust manifold and muffler section rounds the part to 50 kg. The most practical and buyer-friendly way to present this is to describe it as approximately 48 kg, with some catalogs rounding it to 50 kg.

For website copy, the clean version is:

Approximate weight: 48 kg

Some catalog sources round the unit to 50 kg depending on listing format.

That weight also fits the visual impression from the images. This is clearly a substantial exhaust assembly that should be treated as a heavy industrial part in storage, packing, and installation planning.

Technical Details

Part Number Formats

The main searchable formats are 6127115721 and 6127-11-5721. Both appear in public listings and catalogs, so both should be included in product content to capture different buyer search habits.

Product Type

Public sources identify the item as a muffler or muffler assembly in the exhaust category. UCASLAR lists it under exhaust, and 777parts places it in the exhaust manifold and muffler unit.

Main Machine Family

The clearest machine-side references link the part to Komatsu D155 and D355 families, with D155A-2 specifically named on one public listing.

Engine Family

The most visible engine-side references connect this number with S6D155-4-R, S6D155-4A, S6D155-4AA, S6D155-4B, and S6D155-4S.

Approximate Weight

48 kg is the most repeated public value, while some catalogs round the part to 50 kg.

Why This Muffler Matters in Daily Operation

A large Komatsu dozer works in conditions that put constant stress on the exhaust system. Earthmoving, pushing, quarry work, and site preparation all involve sustained engine load. In those conditions, the silencer has to do its job without cracking, loosening, or creating extra strain on neighboring components. A properly built exhaust unit helps the machine maintain a stable external exhaust path and a more controlled operating sound profile.

When the exhaust silencer is near the end of service life, the problem is not only noise. A poor unit can contribute to visible leakage, extra vibration, support stress, and a less dependable installation around the engine bay. That is why this product number is usually searched by buyers who are already dealing with a repair plan, a rebuild, or a scheduled machine refresh. Replacing the muffler can help restore a more solid exhaust arrangement and reduce unnecessary load on the surrounding brackets and pipes.

Benefits of a High-Quality Replacement

Better Installation Accuracy

A properly made Komatsu exhaust silencer should align more naturally with the inlet connection and the upper mounting arrangement. This reduces workshop time and helps avoid forced positioning during installation.

Stronger Exhaust System Stability

Because the unit is relatively heavy, shell strength and bracket integrity matter. A dependable replacement helps the full exhaust assembly stay more stable under vibration and engine movement.

Less Stress on Related Hardware

When the muffler seats correctly, surrounding clamps, pipe sections, and support brackets are less likely to carry compensating loads caused by misalignment. That can improve the service life of the wider exhaust system.

Better Long-Term Value

For fleet owners and contractors, the benefit is not just that one part gets replaced. The real value is that the repaired exhaust setup is more stable and less likely to cause repeat work in the near term.

Installation Guidance

Before ordering, confirm the machine family and, where possible, the engine family or serial reference. Public sources strongly support D155, D355, D155A-2, and S6D155-family applications, but heavy equipment can carry previous modifications or mixed replacement history, especially after years of field service. Final fitment confirmation is the safest path before purchase.

Before fitting the replacement, inspect the inlet flange, connected exhaust pipes, support brackets, and nearby mounting points. Since the part weighs about 48 kg, safe handling matters during service. It is also wise to check for cracked supports, worn mating surfaces, or signs of prior misalignment before the new unit is installed. After installation, a short follow-up inspection can help confirm correct seating and stable exhaust alignment.

Why Buy from 3GEN Export

At 3GEN Export, we understand that buyers searching for this Komatsu exhaust part are usually solving a real downtime problem. A D155 or D355 waiting on a muffler replacement can delay production, roadwork, quarry support, and site preparation schedules.

That is why we supply this part as an OEM supplier and deliver all over the world in 5 working days. Our focus is clear product identification, dependable export handling, and fast supply for heavy machinery spare parts.

Final Summary

The 6127115721 / 6127-11-5721 MUFFLER KOMATSU is a heavy-duty exhaust silencer used in Komatsu D155 and D355 family applications, with engine-side catalog references also linking it to S6D155-4-R, S6D155-4A, S6D155-4AA, S6D155-4B, and S6D155-4S. Public weight references center on 48 kg, while some catalog entries round the part to 50 kg. The product images support that classification by showing a cylindrical steel body, reinforced side inlet, and strong upper mounting bracket suited to hard industrial use.

As 3GEN Export, we offer this product as an OEM supplier and deliver worldwide in 5 working days.