The K-JC 503 mini mobile jaw crusher is Komplet America’s smallest and most compact tracked jaw crusher — engineered specifically for tight-access urban demolition, residential renovation, and small contractor operations where larger machines simply can’t fit. At ~7,500 lb with a 9’8″ transport length and 5′ transport width, the K-JC 503 fits where bigger crushers can’t go.
This guide is the comprehensive product overview, with a specific focus on how every feature contributes to minimizing work-site downtime — the metric that ultimately determines whether a small contractor recoups equipment cost or struggles to break even. Includes full verified specs, the unique features that distinguish the K-JC 503 from generic compact crushers (including the ultrasonic feed sensor that no other compact mobile jaw crusher in this size class offers), target operations, ecosystem positioning, and FAQ.
Design Philosophy: Compact Doesn’t Mean Compromised
Most compact tracked jaw crushers in the K-JC 503’s size class fall into one of two categories: extremely small machines with limited capability, or repackaged industrial equipment that’s nominally compact but lacks the engineering refinement of larger Komplet products. The K-JC 503 sits in neither category — it’s a fully-engineered Komplet jaw crusher with the same hydraulic adjustment, dust suppression, wireless remote, and tracked mobility as its larger siblings, scaled into the smallest practical footprint for limited-access work.
That positioning serves a specific customer profile: small demolition contractors working urban and residential sites, renovation specialists with tight-access projects, landscape supply yards entering RCA production, and rental fleet operators serving small-job market segments. For these operations, the K-JC 503’s compact footprint isn’t a marketing claim — it’s a functional requirement that determines whether the equipment fits the job at all.
K-JC 503 Full Specifications
Throughput and Capacity
- Production rate: Up to 34 US tph (depending on material and operating conditions)
- Output size range: 3/4″ to 3-1/4″ (hydraulically adjustable via wireless remote)
- Recommended max feed size: Approximately 10″ minus (pre-processed material)
Crushing Chamber
- Jaw size: 19″ × 12″
- Jaw type: Single-toggle, hydraulically adjustable
- Compatible materials: Concrete, brick, masonry, softer stone, cold asphalt, natural rocks
Engine and Drive
- Engine: Tier 4 Final Diesel
- Horsepower: 25 HP
- Drive system: Hydraulic, supporting variable feeder speed and conveyor control
Mobility and Setup
- Mobility: Self-propelled rubber tracks, wireless remote control
- Working size (L × W × H): 15′ × 5′ × 6’6″ (deployed for operation)
- Transport size (L × W × H): 9’8″ × 5′ × 7’2″ (folded for road transport)
Physical Specifications
- Weight: 7,496 lb
- Base unit price + magnetic attachment: $108,695.73 — pricing subject to change based on dealer location, configuration, and current availability
- Warranty: 12 months / 1,000 hours (whichever is earlier)
How the K-JC 503’s Features Minimize Downtime
Downtime on a small contractor job site has compounding consequences — operator labor costs accumulating without production, project schedule extending, additional rental days for support equipment, and missed bid windows for the next project. Every feature on the K-JC 503 is engineered with this reality in mind.
1. Ultrasonic Jaw Chamber Level Sensor
This is the K-JC 503’s most distinctive uptime feature — and one no other compact tracked jaw crusher in this size class offers. An integrated ultrasonic sensor above the crusher inlet automatically monitors material level in the jaw chamber and controls the feed belt accordingly. When the chamber gets too full, the sensor slows or pauses the feed belt; when material clears, feed resumes. The result: dramatic reduction in over-feed jamming (one of the largest causes of downtime on small jaw crushers) without requiring the operator to constantly monitor feed rate.
2. Hydraulically Adjustable Jaw Setting
The closed-side setting (CSS — the gap between jaw plates that determines output size) is hydraulically adjustable via wireless remote. Switch between coarse output (3-6″ for riprap or oversized fill) and fine output (3/4″ minus for spec aggregate) without manual tooling, without shutdown, without service intervention. Adjust during operation as material composition or customer demand changes — production continues while configuration changes happen.
3. Loading Belt with Feeding Speed Adjustment
The loading belt feed speed is adjustable, letting operators match feed rate to material characteristics. Slower for materials requiring more retention time in the chamber (wet material, fines-heavy feed); faster for clean dry aggregate at maximum throughput. Combined with the ultrasonic sensor’s automatic feed control, this gives operators both manual control and automatic protection.
4. Standard Dust Suppression
Water-spray dust suppression is standard equipment via integrated nozzles. Connect a garden-hose water line, the system runs automatically. Beyond OSHA crystalline silica compliance (PEL of 50 ug/m3 averaged over 8 hours), dust control reduces wear-part replacement frequency, extends component life, and prevents the dust-accumulation problems that cause unscheduled downtime on machines without active suppression.
5. Wireless Remote Control
Every primary function — drive, feeder rate, jaw direction, conveyor folding, emergency stop — controlled remotely. One operator handles the full machine from a position with optimal visibility (typically the loader cab while feeding). No second operator needed; reduces labor cost; better visibility means earlier detection of feed problems before they become jams.
6. Self-Propelled Tracked Mobility
Drive the machine into position via wireless remote — no specialized rigging, no crane work, no dedicated setup crew. Tracks deliver better stability than wheels on uneven demolition sites and don’t require tire pressure management. The 5′ transport width (compared to 8’6″ maximum width on standard road trailers) means the K-JC 503 can be transported on smaller, more accessible trailers than larger compact crushers.
7. Quick Setup Time
Under 15 minutes from transport configuration to operating, typical for the K-JC 503. The single-operator deployment via wireless remote eliminates the multi-person setup teams larger machines require. On small contractor projects where the crusher gets deployed and removed on the same day, fast setup directly determines whether the equipment is economic for the project.
8. Optional Oversize Scalper Attachment
Mounted directly on the hopper, the optional oversize scalper attachment screens out oversized debris BEFORE it enters the jaw chamber — preventing jams at the most upstream point in the workflow. Particularly valuable for operations processing variable demolition feed where oversize pieces sometimes appear unexpectedly. The attachment further reduces the dominant cause of jaw crusher downtime: oversized material entering a chamber that can’t process it.
9. Optional Magnetic Attachment for Rebar Recovery
The base unit price includes the magnetic attachment, which lifts ferrous metal off the discharge conveyor into a separate clean pile during crushing. Critical for demolition concrete with rebar — recovers metal automatically rather than requiring manual sorting. Recovered rebar typically sells for $100-$300+/ton as scrap, adding revenue while improving RCA quality.
What the K-JC 503 Crushes
Demolition Concrete (with Rebar)
Residential foundation removal, sidewalk replacement, driveway demolition, small commercial slab removal. The magnetic attachment recovers rebar; the hydraulically adjustable jaw produces RCA at the spec size your end use requires (3/4″ minus base, 1-1/2″ drainage, oversized fill).
Brick and Masonry
Demolition of small brick structures, masonry walls, chimney removal. Crushed brick goes into recycled aggregate, decorative landscape material, or fill. Whole-brick salvage happens before crushing for character/historic reuse markets.
Cold Asphalt
Asphalt millings and small-area asphalt removal projects. Output works as RAP for cold-patch applications, base aggregate, or fill. Asphalt requires CSS adjustment compared to concrete; the hydraulic adjustment makes the switch quick.
Natural Stone and Excavated Rock
Site preparation hitting ledge rock, small-volume excavation projects, landscape supply for raw rock. The K-JC 503’s compact footprint supports residential and small commercial sites where larger crushers can’t deploy.
Softer Stone
Limestone, sandstone, gypsum, and similar softer materials. Wear-part life is significantly longer on softer feeds than on hard abrasive granite — favoring the K-JC 503’s economic position in markets dominated by these materials.
Who the K-JC 503 Is For
Small Demolition Contractors
Residential and small commercial demolition operations producing 50-500 tons/month of concrete and masonry waste. The K-JC 503’s $108,695 entry price is meaningfully below larger crushers, supporting capital decisions for operations whose project pipeline doesn’t justify a K-JC 704 PLUS.
Renovation Specialists
Contractors working on building renovations and adaptive reuse projects often face concrete and masonry removal in tight-access conditions. The K-JC 503’s 5′ transport width fits more access scenarios than larger machines.
Landscape Supply Yards Entering RCA Production
Landscape supply yards adding RCA to their product mix benefit from the K-JC 503’s smaller capital commitment as they prove out market demand. Once volume justifies it, they can scale up to a K-JC 604 or K-JC 704 PLUS without losing the K-JC 503 — many operations keep both for different project types.
Rental Fleet Operators Serving Small-Job Markets
Equipment rental operations serving residential demolition contractors, small concrete removal jobs, and tight-access projects benefit from the K-JC 503’s transportability and broad project applicability. The compact size translates directly to rental utilization.
Excavation Contractors with Small-Volume Rock
Excavation operations occasionally hitting ledge rock or excavated stone benefit from on-site processing capability without committing to a larger crusher’s capital. The K-JC 503 handles small-volume rock processing economically.
How the K-JC 503 Fits in a Complete Operation
With the Kompatto 221 Vibrating Scalping Screen (Most Popular Pair)
The Kompatto 221 — Komplet’s compact vibrating scalping screen at ~$104,935 — is the natural pair for the K-JC 503. Up to 90 US tph screening capacity (well above the K-JC 503’s 34 US tph crushing throughput) means the screener never bottlenecks the operation. Together they deliver complete crushing-and-screening capability for tight-access work at a combined capital of approximately $213,630.
Standalone Operation
Many K-JC 503 owners run the machine without a paired screener, especially for projects where output goes directly to fill, riprap, or oversized drainage applications that don’t require sized spec product. The hydraulically adjustable jaw produces output ranging from 3/4″ minus (suitable for many base material applications) up to 3-1/4″ — a useful range that doesn’t require additional screening for many uses.
Scaling Up Path
Operations starting with the K-JC 503 and growing to consistent demand for higher throughput typically scale up to the K-JC 604 (up to 55 US tph) or the K-JC 704 PLUS (up to 90 US tph, Komplet’s best-seller). Many keep the K-JC 503 in the fleet for tight-access work where the larger machine can’t deploy.
Frequently Asked Questions
How does the K-JC 503 minimize downtime compared to similar compact jaw crushers?
Several features specifically address downtime: the ultrasonic chamber level sensor automatically prevents over-feed jamming, hydraulically adjustable jaw setting eliminates manual configuration changes, optional oversize scalper attachment screens problem material before it enters the jaw, standard dust suppression reduces dust-accumulation downtime, wireless remote enables single-operator awareness of developing problems, and quick setup means the machine is producing within 15 minutes of arrival rather than after a multi-hour deployment.
How much can the K-JC 503 crush per hour?
Up to 34 US tph depending on material and operating conditions. Real-world production varies based on material type (clean concrete runs faster than mixed feed), operator skill, output size requirement (finer output requires more time), and operating conditions. The ‘up to’ rating is a best-case scenario metric, not a guaranteed throughput.
What size material can the K-JC 503 crusher process?
The jaw inlet opening is 19″ × 12″. Recommended maximum pre-processed feed size is approximately 10″ minus — pieces larger than this should be pre-broken with an excavator-mounted hydraulic breaker before feeding. Output size is hydraulically adjustable from 3/4″ to 3-1/4″ via the wireless remote.
Can the K-JC 503 handle reinforced concrete with rebar?
Yes, with the magnetic attachment (included in the base unit price). The magnetic attachment lifts ferrous metal off the discharge conveyor during crushing. The hydraulically adjustable jaw and reverse functions handle the demolition concrete itself. Recovered rebar typically sells as scrap metal, adding revenue while keeping RCA cleaner.
How long does setup take on the K-JC 503?
Under 15 minutes from transport configuration to operating, typical. The machine is self-propelled tracked with wireless remote control, hydraulically folding conveyor, and a quick-deploy design. One operator drives it into position, deploys the conveyor, runs a brief warm-up, and starts feeding.
What does the K-JC 503 cost?
Base unit price plus magnetic attachment is $108,695.73. Pricing subject to change based on dealer location, configuration, and current availability. For current pricing, contact us or call 908-369-3340. Komplet Capital financing offers 24-hour approval, 100% financing, 3-6 year terms. Section 179 tax deduction applies.
Can I rent a K-JC 503?
Yes — through Komplet’s authorized dealer and rental network. Find your local Komplet dealer or call 908-369-3340. Many rental partners offer rent-to-own arrangements where rental payments credit toward eventual purchase.
How does the K-JC 503 compare to the K-JC 604 and K-JC 704 PLUS?
The K-JC 503 is the smallest and most compact: up to 34 US tph, 19″x12″ jaw, ~7,500 lb, ~$108,695. The K-JC 604 is the mid-range option: up to 55 US tph, 23″x16″ jaw, ~19,400 lb, ~$205,030. The K-JC 704 PLUS is Komplet’s best-seller: up to 90 US tph, 27″x16″ jaw, ~26,455 lb, ~$241,255. Choose based on throughput target, jaw opening required, transport requirements, and capital position. The K-JC 503 specifically excels at tight-access urban work where larger machines can’t deploy.
What’s the warranty on the K-JC 503?
12 months / 1,000 hours, whichever comes first. Komplet America’s parts inventory is forecasted 12 months in advance, supporting fast wear-part availability when service items are needed. Authorized dealers across North and Central America provide local service support.
Final Thoughts
The K-JC 503 is engineered for the operations where downtime hurts the most — small contractor projects with tight margins, daily-deployment rental scenarios, and tight-access urban work where larger crushers simply can’t fit. Every feature, from the ultrasonic feed control to the hydraulic jaw adjustment to the optional oversize scalper attachment, is designed to keep the machine running productively rather than sitting idle. Combined with Komplet America’s parts inventory forecasting and authorized dealer network, the K-JC 503 delivers the uptime small contractors need to make on-site crushing economically viable.
Browse the K-JC 503 product page for full specifications and configuration options, or call us and we’ll help you spec the right combination of equipment for your operation.
Ready to Talk K-JC 503?
- Call 908-369-3340
- Email [email protected]
- Schedule a demo or request a quote
- Find your local Komplet dealer for rental availability
- Ask about our 12-month / 1,000-hour warranty and equipment financing options
Never enough — that’s how we approach service, support, and helping small contractors keep the K-JC 503 running productively year-round.
