Q-01
ISO 9001:2015
Our quality management system is certified to ISO 9001:2015. Systematic quality control is applied at every stage, from raw material intake to shipment.
İSTANBUL — 41.0048° N / 29.1642° E
POWER AT SEA TRUST ON COURSE
Mechanical and hydraulic marine gearboxes built in İstanbul since 1977. GG25 cast iron housing, precision CNC gear machining, and dynamic load testing for every unit.
ISO 9001:2015 · CE 2006/42/EC · EVERY UNIT IS TESTED
1977
FOUNDED
30,000+
GEARBOXES
30+
EXPORT COUNTRIES
0–300HP
POWER RANGE
COMPANY
Half a Century of Manufacturing Discipline
Broad CompatibilityReduction ratios from 1:1 to 3:1, SAE 1–5 bellhousings
Rotation CompatibilityCompatible with clockwise and counter-clockwise engine rotation and twin-engine installations
Quiet OperationGround gear surfaces, smooth power transmission
Köysan® has been manufacturing marine gearboxes at its production facility in the İMES Industrial Estate, Dudullu, İstanbul since 1977. Nearly half a century of accumulated expertise has made us one of Türkiye's most established marine gearbox manufacturers.
Our products serve a broad range of applications — from fishing boats and pleasure yachts to commercial vessels and speedboats. Our flexible design adapts to diverse engine configurations, and twin-engine compatibility ensures the right solution for every project.
VISION
To extend our range beyond 500 HP, produce gearboxes with Türk Loydu class approval, and become a preferred Turkish brand in international markets.
MISSION
We deliver the appropriate torque, operating speed and service life for each vessel through nearly fifty years of manufacturing experience and continuously evolving engineering.
PRODUCT RANGE
Marine Gearbox Models
Five models, two clutch types. Click a card to open the full technical file — specifications, performance tables and applications.
A-1MECHANICAL
- MAX RPM
- 4,000 rpm
- DRY WEIGHT
- 51 kg
- REDUCTION
- 1.0:1 · 1.5:1 · 2.0:1 · 2.5:1
TECHNICAL FILE
H-1HYDRAULIC
- MAX RPM
- 3,000 rpm
- DRY WEIGHT
- 110 kg
- REDUCTION
- 1.0:1 · 1.5:1 · 2.0:1 · 2.5:1 · 3.0:1
TECHNICAL FILE
H-2HYDRAULIC
- MAX RPM
- 3,000 rpm
- DRY WEIGHT
- 100 kg
- REDUCTION
- 2.0:1
TECHNICAL FILE
H-3HYDRAULIC
- MAX RPM
- 3,000 rpm
- DRY WEIGHT
- 150 kg
- REDUCTION
- 1.0:1 · 1.5:1 · 2.0:1 · 2.5:1 · 3.0:1
TECHNICAL FILE
H-4HYDRAULIC
- MAX RPM
- 4,500 rpm
- DRY WEIGHT
- 40 kg
- REDUCTION
- 1.0:1 · 1.5:1 · 2.0:1 · 2.5:1
TECHNICAL FILE
GEARBOX SELECTOR
Which model fits your vessel?
Answer two questions for an initial recommendation. For the final selection, contact our technical team with your engine power and operating speed.
01 — APPLICATION
02 — CLUTCH PREFERENCE
Make a selection — the recommendation will appear here
FEATURED REFERENCE — N-16
TCG NUSRET
The 2011-built replica of the legendary Nusret minelayer — symbol of the Çanakkale Naval Victory — is equipped with a Köysan® marine gearbox. TCG Nusret serves as an active museum ship sailing regular routes between Samsun, İskenderun, Çanakkale and İzmir. In addition, Köysan® gearboxes continue to operate reliably aboard approximately 100 Turkish Naval Forces vessels.
~100TURKISH NAVAL VESSELS EQUIPPED WITH KÖYSAN®
QUALITY & PRODUCTION CONTROLS
Quality Verified at Every Stage
Q-02
CE — 2006/42/EC
Our products bear the CE marking in accordance with the EU Machinery Directive (2006/42/EC) and meet the applicable requirements for placement on the European market.
Q-03
Dynamic Load Testing
Every gearbox is tested under dynamic load after production; ahead–neutral–astern shifting, torque transmission and oil pressure parameters are verified.
Q-04
Material Quality
Housing: high-grade cast iron (GG25). Gears: heat-treated alloy steel. Clutch plates: high-friction composite material.
INCOMING INSPECTION→
CNC MACHINING→
HEAT TREATMENT→
ASSEMBLY→
DYNAMIC LOAD TEST→
SHIPMENT
Technical Guide
Choosing the Right Gearbox
Technical guides drawn from half a century of manufacturing experience, to help you select the right gearbox and keep it running.
Marine Gearbox Failure Symptoms and Maintenance Checklist
Learn about common failure symptoms, early warning signs, and the periodic maintenance checklist to prevent costly repairs in marine gearboxes.
Read the guideATF Selection and Oil Change Intervals in Marine Gearboxes
Learn about choosing the right transmission oil, the break-in process, periodic oil change intervals, and critical maintenance tips to extend your gearbox's life.
Read the guideMechanical vs. Hydraulic Clutch: Which is Right for Your Boat?
Learn the differences between mechanical and hydraulic clutch systems in marine gearboxes, their advantages, and how to make the best choice for your boat.
Read the guideCONTACT
Request a Quote or Technical Information
Complete the form to create a draft in your e-mail application. You can also open the same message in WhatsApp.