MKIV hydraulic unit 3
8
Hydraulic length adjusting cylinder (optional)
Pressure requirements
The hydraulic length adjusting cylinder requires a pressure of max 5000 lb (350 bar) to develop rated pull force
on the headstay. The hydraulic pressure for the cylinder can be provided by a high pressure manual system or the
boats power unit. If the cylinder is used with a power unit that provides less than 5000 psi (350 bar), a hydraulic
intensifier is required to step up the pressure. Either power source requires the use of a zero-leak control valve so
the pressure to the cylinder doesn’t bleed down over time.
Hydraulic cylinder hose connection
The cylinder has a -4 JIC fitting. Choose appropriate hose and end fitting.
Cylinder gas
Cylinder is shipped without gas. Fill fitting is a Schroeder type. For best clean performance use nitrogen or argon
gas pressurized to 50 - 60 psi (3.45 - 4.48 bar).
Specifications:
Stroke: Unit 3: 100 mm (4")
Performance:
Cylinder pull force lb
12000
10000
8000
6000
4000
2000
0
6000
4000
2000
Hydraulic pressure in LB
Cylinder pull in LBS
0
Cylinder pull force kg
6000
5000
4000
3000
2000
1000
0
400
200
100
Hydraulic pressure in BAR
Cylinder pull in KG
300
0
WARNING! Relieve all pressure prior to disconnecting. Only work on cylinder and connections
if you are a hydraulic technician.
Leak check
To perform leak check, run furler in a single direction for 5 – 10 seconds. If installation was completed with empty
hoses, increase the run time to 10 – 30 seconds. Perform the following:
1) Confirm hose run is correct by verifying operation of intended function.
2) Inspect each fitting for leakage.
3) Tighten fitting as necessary.
4) Repeat procedure for all functions.
IMPORTANT!
If installation was completed with empty hoses, check the oil level indicator, and add oil as necessary.
One-way function flush
Flush the pump motor through the power unit system filter by running furler in a single direction. Run in same
direction as previous step. This process helps ensure system cleanliness by depositing contaminates into
the power unit system filter.
Hydraulic connection to furling unit
Furling unit has SAE female straight thread ports to accept -6 ORB fittings. Use male to male adapters in the furler
so you can use female swivel hose ends. Use -6 JIC X -6 ORB adapters - Stainless steel
IMPORTANT!
Do not use PTFE tape or sealant on threaded connections to Harken ports. Using PTFE tape can damage threads.
Hydraulic oil
Use only hydraulic oil ISO 46 grade or equivalent.
IMPORTANT!
Hydraulic oil may damage paint and some surfaces.
Preassembly
Hydraulic System
CAUTION! Hydraulic oil may cause skin irritation.
