Ultraflex UC95-OBF Series Front Mount Outboard Hydraulic Steering Cylinder

The Ultraflex UC95-OBF/1, UC95-OBF/2 and UC95-OBF/3 are balanced front-mount hydraulic steering cylinders for compatible single- or twin-outboard installations up to 175HP total, where boat speed does not exceed 55mph / 48 knots. All three models share the same cylinder body, nominal 95cc volume, 186mm stroke, 30mm bore, 3/8in hose fittings and DN5 quick-connect bleed fittings. Select the version required by the Ultraflex Application Guide: the UC95-OBF/1 43515D with a straight link arm, the UC95-OBF/2 43535K with a shaped link arm or the UC95-OBF/3 43516F with a curved link arm.

Special-order notice: The UC95-OBF/2 shaped-arm version and UC95-OBF/3 curved-arm version are special-order products and are subject to a supplier lead time. Contact us for the current estimated lead time before ordering. These models should not be ordered on the assumption of immediate dispatch.

Product Identification

• Brand: Ultraflex
• Product range: UC95-OBF
• Product category: Front-mount outboard hydraulic steering cylinder
• Available models: UC95-OBF/1 / UC95-OBF/2 / UC95-OBF/3
• Manufacturer part numbers: 43515D / 43535K / 43516F
• Straight-arm model: UC95-OBF/1
• Straight-arm part number: 43515D
• Shaped-arm model: UC95-OBF/2
• Shaped-arm part number: 43535K
• Curved-arm model: UC95-OBF/3
• Curved-arm part number: 43516F
• UC95-OBF/1 availability: Subject to stock availability
• UC95-OBF/2 availability: Special order; supplier lead time applies
• UC95-OBF/3 availability: Special order; supplier lead time applies
• Cylinder type: Balanced, double-acting hydraulic cylinder
• Mounting position: Front mount
• Installation point: Outboard engine tilt tube
• Catalogue nominal volume: 95cc / 5.8cu.in
• Stroke: 186mm / 7.3in
• Internal diameter: 30mm / 1.18in
• Maximum application: 175HP total
• Maximum boat speed: 55mph / 48 knots
• Racing applications: Not suitable
• Application: Compatible single- or twin-outboard hydraulic steering systems

What Is This Hydraulic Cylinder Used For?

The Ultraflex UC95-OBF converts hydraulic fluid movement from a compatible steering helm into mechanical movement at the outboard engine. When the steering wheel is turned, the helm sends fluid to one side of the cylinder, moving the cylinder body and link-arm assembly to steer the engine.

The balanced cylinder design provides the same effective hydraulic volume in both steering directions. This produces an equal number of steering-wheel turns from port to starboard and from starboard to port when the cylinder is installed in a correctly specified hydraulic steering system.

The UC95-OBF range can be used in:

• Compatible single-outboard installations
• Compatible twin-outboard installations using one cylinder and the correct tie bar
• Single-steering-station systems
• Compatible dual-steering-station systems
• New marine hydraulic steering installations
• Replacement of an existing compatible UC95-OBF cylinder

The cylinder does not independently determine the permitted engine horsepower or complete steering-system capacity. The helm pump, cylinder, hydraulic hoses, tie bar, engine arrangement and boat rating must be approved as one complete system.

What Is Included?

The selected Ultraflex UC95-OBF cylinder is supplied with:

• UC95-OBF cylinder body with hydraulic rod
• Adjustable hydraulic fittings
• Bleed valves
• Cylinder mounting brackets or bull horns
• Selected model-specific link arm
• Two-piece tilt-tube mounting rod
• Tilt-tube rod locking pin
• Two locknuts and two washers for the tilt-tube rod
• Eight plastic spacers
• Two steel spacers
• Adjustment-collar ring nut
• Installation locknuts
• Lock washers
• Short hexagon-head fixing screw
• Long hexagon-head fixing screw
• Plastic hose for hydraulic-circuit bleeding

Model-specific link arm supplied:

• UC95-OBF/1: Straight link arm
• UC95-OBF/2: Shaped link arm
• UC95-OBF/3: Curved link arm

Not included:

• Hydraulic steering helm pump
• Steering wheel
• High-pressure hydraulic hoses
• Hydraulic steering oil
• Complete helm-filling kit
• Oil-bottle adapter
• Automatic purging equipment
• A92 twin-engine tie bar
• Second hydraulic cylinder
• Additional steering-station plumbing
• Outboard engine
• Engine components not specifically listed as supplied

The included plastic bleed hose is not a complete steering-system filling kit. The correct oil bottle, adapter and additional filling equipment must be obtained separately where required.

What Is the Difference Between the Three Models?

All three UC95-OBF models use the same basic cylinder body and share the same hydraulic specifications. The model suffix identifies the geometry of the supplied engine link arm.

• UC95-OBF/1 / 43515D: Straight link arm
• UC95-OBF/2 / 43535K: Shaped or offset link arm
• UC95-OBF/3 / 43516F: Curved link arm

The link arm connects the hydraulic cylinder mechanism to the outboard engine's tiller arm. Different engines position the tiller-arm connection, tilt tube and surrounding components differently. The three arm geometries allow the cylinder to suit different approved engine installations when combined with the correct spacer arrangement.

The UC95-OBF/2 is not more powerful than the UC95-OBF/1, and the UC95-OBF/3 does not have a different hydraulic stroke or cylinder capacity. The only stated model-specific difference is the supplied link-arm geometry.

Do not select the version by appearance alone. Use the current Ultraflex Application Guide for the exact engine manufacturer, model, horsepower and year.

Special-Order Availability and Lead Time

The following ordering conditions apply:

• UC95-OBF/1 / 43515D straight-arm version: Supplied subject to normal stock availability
• UC95-OBF/2 / 43535K shaped-arm version: Special order; supplier lead time applies
• UC95-OBF/3 / 43516F curved-arm version: Special order; supplier lead time applies

The UC95-OBF/2 and UC95-OBF/3 are not standard immediate-dispatch variants. The current lead time can vary according to manufacturer and supplier availability.

Contact us before placing an order for either special-order version so that the current estimated delivery time can be confirmed.

The lead time does not determine which model is suitable. The correct arm must still be selected from the Ultraflex Application Guide. A special-order version should not be substituted with a different arm type solely because the alternative is available sooner.

Which Outboard Engines Are Compatible?

The UC95-OBF range is recommended for compatible outboard installations where:

• Total engine power does not exceed 175HP
• Boat speed does not exceed 55mph / 48 knots
• The installation is not a racing application
• The engine has a compatible tilt tube
• The engine has a compatible tiller-arm arrangement
• The correct straight, shaped or curved link arm is selected
• The supplied spacers can be installed in the required arrangement
• The boat manufacturer's maximum engine-power rating is not exceeded
• The complete steering system is correctly specified

Exact compatibility must be confirmed using the current Ultraflex UC95-OBF Application Guide. The guide determines:

• Whether the engine accepts a UC95-OBF cylinder
• Whether the UC95-OBF/1, UC95-OBF/2 or UC95-OBF/3 is required
• Which engine-link screw is used
• Which spacers are required
• Where each spacer must be positioned
• Whether additional approved components are required
• Whether the installation provides sufficient steering and tilt clearance

Compatibility cannot be confirmed from engine brand or horsepower alone.

Do not bend, drill, grind, weld or otherwise modify the supplied link arm or cylinder components to make an incorrect model fit.

Can It Be Used with Twin Outboards?

The UC95-OBF can be used with compatible twin-outboard installations using a single cylinder, provided that:

• Combined engine power does not exceed 175HP
• Boat speed does not exceed 55mph / 48 knots
• Both engines are compatible with the selected UC95-OBF version
• The correct straight, shaped or curved link arm is installed
• A compatible Ultraflex A92 tie bar is used
• The engine-centre dimensions are within the selected tie-bar adjustment range
• The complete system follows the Ultraflex application and installation data

The A92 tie bar is sold separately. Available A92 versions include:

• A92/700 / 40892V: Adjustable for engine centres from 550mm to 700mm
• A92/950 / 40893X: Adjustable for engine centres from 700mm to 950mm

Tie-bar compatibility must be checked for the exact engine pair and engine-centre measurement before ordering.

Which Hydraulic Helm Pump Is Compatible?

The hydraulic helm must be selected according to the UC95-OBF cylinder volume, required steering effort and required number of steering-wheel turns from lock to lock.

Ultraflex pairs the UC95-OBF cylinder with the UP20F 20cc/rev front-mount helm pump in its HyTech-OBF hydraulic steering package.

Using the installation-manual cylinder volume of approximately 94cc:

• 94cc ÷ 20cc per revolution = approximately 4.7 steering-wheel turns lock to lock

Ultraflex advises against steering combinations with fewer than approximately four turns or more than approximately eight turns lock to lock.

For the same cylinder:

• A lower-displacement helm normally produces more steering-wheel turns and lower steering effort
• A higher-displacement helm normally produces fewer steering-wheel turns and higher steering effort

Before selecting a helm pump, confirm:

• Helm displacement per revolution
• Cylinder volume
• Required steering-wheel turns
• Number of steering stations
• Maximum operating pressure
• Steering-wheel diameter
• Hose and fitting specification
• Complete Ultraflex system approval

The documented UP20F pairing does not mean that every installation can be selected without reference to the current Ultraflex system data.

Which Hydraulic Hoses and Oil Are Required?

The UC95-OBF is fitted for compatible 3/8in high-pressure flexible hydraulic hose. It also uses DN5 quick-connect bleed fittings.

Use:

• Correctly rated marine hydraulic steering hoses
• Compatible Ultraflex hose fittings or an approved preassembled hose kit
• Ultraflex OL150 hydraulic steering oil
• The filling and bleeding equipment specified for the selected helm
• Approved hydraulic thread-sealing products where specifically required

Do not use:

• Unapproved low-pressure hose
• Contaminated hydraulic oil
• An unidentified fluid already drained from another steering system
• PTFE or Teflon tape where fragments could enter the hydraulic circuit
• Automotive brake fluid
• Engine oil
• Gearbox oil

Hydraulic hoses, OL150 oil and the complete filling equipment are sold separately.

Hydraulic Specifications

• Cylinder design: Balanced and double acting
• Product-page nominal volume: 95cc / 5.8cu.in
• Installation-manual volume: 94cc / 5.7cu.in
• Product-page output force: 278kg / 613lb
• Theoretical maximum thrust: 354kg / 780lb at 70 bar / 1000psi
• Maximum operating pressure: 70 bar / 1000psi
• Internal diameter: 30mm / 1.18in
• Stroke: 186mm / 7.3in
• High-pressure hose connection: 3/8in
• Bleed fitting: DN5 quick connect
• Specified hydraulic oil: Ultraflex OL150
• Operating-temperature range: -18°C to +77°C / 0°F to +170°F

The theoretical 354kg / 780lb thrust is calculated at the maximum 70-bar pressure condition. Ultraflex states that this represents an extreme operating condition rather than the cylinder's normal steering output.

Published Technical Data Note

Ultraflex's product page and installation manual publish slightly different volume and force figures:

• The product page lists 95cc / 5.8cu.in and an output force of 278kg / 613lb
• The installation manual lists 94cc / 5.7cu.in and a theoretical maximum thrust of 354kg / 780lb at 70 bar

The difference between 94cc and 95cc reflects the nominal figures used in separate Ultraflex technical documents.

The 354kg figure is a theoretical extreme-pressure calculation and should not be treated as the cylinder's normal operating output.

For product identification, use the exact model and manufacturer part number. For installation, helm selection, pressure limits and engine compatibility, follow the current Ultraflex installation manual and Application Guide.

Dimensions and Fitment

• Approximate overall width: 551mm / 21.7in
• Manufacturer drawing vertical reference: 78mm / 3.08in
• Cylinder stroke: 186mm / 7.3in
• Internal diameter: 30mm / 1.18in
• Mounting location: Outboard engine tilt tube
• Hydraulic hose connection: 3/8in
• Bleed connection: DN5 quick connect
• Packaged weight: Approximately 8kg / 18lb

Before ordering, confirm sufficient clearance for:

• Full port and starboard cylinder travel
• Complete outboard-engine tilt movement
• The selected straight, shaped or curved link arm
• Hydraulic hose routing
• Bleed-valve access
• Engine cowling movement
• Transom and splashwell structure
• Jack plate movement where fitted
• Control cables, wiring and other rigging components

The engine must be able to steer and tilt through its complete permitted range without the cylinder, link arm, hoses or fittings contacting another component.

A jack plate changes the clearance between the engine, transom, splashwell and steering cylinder. Clearances must be rechecked through the combined steering and tilt range where a jack plate is installed.

Construction and Design

• Balanced hydraulic cylinder
• Double-acting operation
• Adjustable boss-style hydraulic fittings
• DN5 quick-connect bleed fittings
• High-resistance stainless-steel ULTRABOLT connection bolt
• Replaceable cylinder end caps
• Patented split and pinned mounting rod
• Two-piece tilt-tube rod for easier installation
• Bushings designed to prevent friction with the engine tilt tube
• Model-specific straight, shaped or curved link arm
• Plastic and steel spacer system
• Adjustment collar for installation alignment
• Components manufactured for marine hydraulic steering applications

The split mounting rod allows the cylinder to be installed around the engine tilt-tube arrangement without requiring the same insertion clearance as a conventional one-piece rod.

The anti-friction bushings reduce direct friction between the mounting rod and the engine tilt tube. Replaceable end caps allow specified cylinder-end components to be serviced without replacing the complete cylinder assembly.

Standards and Certification

Ultraflex documentation for the UC95 hydraulic steering cylinder references:

• Recreational Craft Directive 2013/53/EU
• EN ISO 10592:2017
• ABYC P21
• EC-type examination certificate HSSUFLX024

Ultraflex states that its hydraulic steering systems can operate within an ambient-temperature range of:

• Minimum: -18°C / 0°F
• Maximum: +77°C / +170°F

Certification of the cylinder does not certify an incorrectly selected or installed steering system. The helm, hydraulic hoses, fittings, oil, tie bar, steering wheel and installation must also meet the applicable manufacturer requirements.

Installation, Filling and Use

Installation should be completed by a qualified marine technician familiar with hydraulic steering systems.

Before installation:

• Confirm the exact engine make, model, horsepower and year
• Check the current Ultraflex Application Guide
• Confirm whether the straight, shaped or curved link arm is required
• Verify the required spacer arrangement
• Check the engine tilt tube for corrosion, damage or obstruction
• Inspect the engine tiller arm and connection point
• Confirm that the boat and engine remain within the stated power and speed limits
• Check that all supplied components are present and undamaged
• Confirm the hydraulic helm displacement
• Confirm the hose size and working-pressure rating
• Check the required steering and tilt clearances

During installation:

• Follow the current Ultraflex installation manual
• Install the specified link-arm screw and spacer arrangement
• Keep the cylinder correctly aligned on the mounting rod
• Use the tightening torques stated in the installation manual
• Check that the engine can tilt through its complete permitted range
• Route hoses away from sharp edges, heat and moving components
• Prevent dirt, water and foreign material from entering the hydraulic system
• Do not modify the cylinder, link arm or mounting hardware
• Do not disassemble components supplied preassembled

Fill and bleed the system using Ultraflex OL150 oil and the approved procedure. Continue bleeding until no air bubbles are visible and the cylinder responds consistently in both directions.

After installation:

• Turn the steering wheel fully from port to starboard several times
• Check that cylinder travel is complete in both directions
• Check that the number of wheel turns is consistent
• Verify that the engine can tilt without obstruction
• Inspect all hydraulic connections for leaks
• Check the helm-fluid level
• Confirm that no hose is stretched, crushed or rubbing
• Check all cylinder-mounting and link-arm hardware
• Confirm that the cylinder reaches the steering limit before the engine contacts an unsuitable mechanical stop
• Repeat the leak and fluid-level inspection after initial operation

Marine steering is a safety-critical system. The boat must not be used if there is leakage, excessive steering-wheel movement, trapped air, restricted engine tilt, loose mounting hardware or abnormal cylinder movement.

Key Features

• Complete Ultraflex UC95-OBF cylinder range
• UC95-OBF/1 manufacturer part number 43515D
• UC95-OBF/2 manufacturer part number 43535K
• UC95-OBF/3 manufacturer part number 43516F
• Straight link arm supplied with UC95-OBF/1
• Shaped link arm supplied with UC95-OBF/2
• Curved link arm supplied with UC95-OBF/3
• UC95-OBF/2 is a special-order product
• UC95-OBF/3 is a special-order product
• Supplier lead time applies to shaped- and curved-arm versions
• Balanced cylinder for equal steering turns in both directions
• Front-mount outboard installation
• Suitable for compatible installations up to 175HP total
• Maximum stated boat speed of 55mph / 48 knots
• Not intended for racing applications
• 95cc / 5.8cu.in catalogue nominal volume
• 186mm / 7.3in cylinder stroke
• 30mm / 1.18in internal diameter
• Adjustable fittings for 3/8in high-pressure hydraulic hose
• DN5 quick-connect bleed fittings
• Maximum operating pressure of 70 bar / 1000psi
• High-resistance stainless-steel ULTRABOLT connection bolt
• Replaceable cylinder end caps
• Patented split and pinned tilt-tube mounting rod
• Anti-friction tilt-tube bushings
• Compatible with approved single- or twin-outboard arrangements
• Compatible with approved single- or dual-station systems
• Documented pairing with the Ultraflex UP20F helm
• Exact engine compatibility must be checked before ordering
• Hydraulic helm, hoses, oil and twin-engine tie bar supplied separately

Frequently Asked Questions

Are the UC95-OBF/2 and UC95-OBF/3 available for immediate dispatch?

No. The UC95-OBF/2 shaped-arm cylinder and UC95-OBF/3 curved-arm cylinder are special-order products. A supplier lead time applies, and the current estimated delivery time should be confirmed before ordering.

Can I choose the straight, shaped or curved arm by looking at the engine?

No. The correct version must be selected using the current Ultraflex Application Guide for the exact engine make, model, horsepower and year. The spacer arrangement is also engine-specific.

Can the supplied link arm be modified?

No. Do not bend, drill, grind, weld or otherwise alter the link arm or cylinder assembly. Modifying the steering components can prevent the system from operating safely.

Do all three versions have the same hydraulic performance?

Yes. The published hydraulic volume, bore, stroke, output figures, hose connections and operating limits are common to all three models. The model-specific difference is the link-arm geometry.

Is the hydraulic helm included?

No. The helm pump, steering wheel, hydraulic hoses, hydraulic oil and filling equipment are sold separately.

Can the cylinder be used with twin outboards?

Yes, where the exact engines and installation are approved. A compatible A92 tie bar is required, and combined engine power must not exceed 175HP.

Is the UC95-OBF suitable for racing boats?

No. Ultraflex states that the UC95-OBF is not intended for racing applications.

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