Boat Hydraulic Steering Systems

How Hydraulic Boat Steering Systems work

Under normal operating conditions, a turn of the steering wheel will send the oil from the helm unit into one of the two connecting hydraulic lines. The oil will be pumped into one of the chambers of the cylinder and either extend or retract the cylinder rod, depending on the steering wheel rotation.

The fluid going out from the other chamber of the cylinder is returned to the helm via the other hydraulic line. There are only two basic components in all the hydraulic steering systems. These are the helm unit and the cylinder, connected by nylon or copper tubing.The helm unit consists of both a hydraulic pump and a valve assembly.

The valve assembly prevents outgoing fluid from returning along the same line, isolates each steering station, locks the rudder and eliminates rudder "feedback" to the helm. The cylinders are double acting and may be balanced or unbalanced, (in which case the rod extends through only one end of the cylinder).

The strength required to drive a boat equipped with an hydraulic steering system is inversely proportional to the number of turns of the wheel lock-to-lock. The wheel turns are determinated by the ratio between the cylinder volume, pump displacement and the free movement of the rudder.

With the same type of cylinder installed on the engine, the less are the turns, the faster is the response but higher is the effort; more wheel turns, slower is the response and lower is the effort. Other factors that can influence steering effort are:

• Vessel speed
• Rudder dimension, or engine power
• Propeller selection
• Hull type (displacement, planing, etc.)
• Sea conditions
• Oil viscosity

Helm Pumps

FEATURES

• Built-in lock valve for positive rudder lock
• Integral relief valve for over-pressure protection
• 3/4" tapered anodized aluminun shaft
  Corrosion proof composite housing
• Easy accessible lock valve and shaft seal for replacement
• Complete with elbow fittings for 3/8” tube
• For use with UC94-OBF, UC68-OBS and UC69-I cylinders only
• Tilt mechanism X52 - 39250 U for UP20 T pump.
• Tilt range of 48º and five locking positions
  NOTE: X52 tilt mechanism fits all Uflex tilt mount rotary and rack and pinion steering helms as well as all Ultraflex tilt mount hydraulic pumps
• X64 - 40198 C square flange permits to
  install the pumps in an intermediate
  dashboard position
  

Rear & Front Mount Helms

Features

• Available in 39 cc/rev (2.4 cu.in/rev) displacement size
• Compact design
• Ball bearing piston race
• Built-in lock valve for positive rudder lock
• Integral relief valve for over-pressure protection
• 3/4” tapered stainless steel shaft
• Easily accessible lock valve and shaft seal for replacement
• Cast iron cylinder rotor for greater durability and longer life
• 1/4” NPT fitting for 3/8” tube
• Complete with elbow fittings
• KIT F (optional) - 39664 Y Remote fill adapter

Tilt Mount Helm Pumps

Features

• Available in three different displacement sizes
• Compact designBall bearing piston race
• Built-in lock valve for positive rudder lock
• Integral relief valve for over-pressure protection
• Stainless steel shaftEasily accessible lock valve and shaft seal for replacement
• Cast iron rotor for greater durability and longer life
• 1/4” NPT fitting for 3/8” tube
• Complete with elbow fittings
• Tilt mechanism:
  X52 - 39250 U
  NOTE: X52 tilt mechanism can be used with the Ultraflex mechanical rotary and rack and pinion steering helms also.
• KIT F (optional) - 39664 Y Remote fill adapter

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