H Y D R A U L I C L I N E A R A C T U AT O R LA17 TABLE OF CONTENTS 1. GENERAL INFORMATION ............................................... p. 01 2. TECHNICAL SPECIFICATIONS and APPLICATION ........ p. 02 3. DESCRIPTION ................................................................. p. 03 3.1 3.2 3.3 3.4 General Pump Unit (HRP17) Reservoir/Bypass Assembly Steering Cylinder 4. INSTALLATION ................................................................. p. 05 4.1 Mechanical 4.2 Hydraulic 4.
1. GENERAL INFORMATION The Accu-Steer LA17 unit is a hydraulic linear actuator designed to interface an autopilot system with a mechanical steering systems such as wire, cable or chain drives. A hydraulic linear actuator consists of a hydraulic drive unit (containing a pump unit, bypass valve and reservoir assembly), a steering cylinder and the interconnecting hoses.
2. TECHNICAL SPECIFICATIONS and APPLICATION Model Number LA17-12 LA17-24 Voltage 12 VDC 24 VDC Output/Sec 1.6 cu in/sec 1.6 cu in/sec Average Motor Amp 4-8 3-5 Solenoid Valve Amp 1.5 AMPS .75 AMP Weight 15 lbs (7 kgs) 15 lbs (7 kgs) The output of the hydraulic reversing pump is 1.6 cu in/sec. The volume of the steering cylinder is approximately 23.5 cu in (385 cubic centimeters). The rudder speed will be approximately 14.7 seconds hard over to hard over (HOH).
3. DESCRIPTION OF OPERATION 3.1 GENERAL The Accu-Steer LA17 is a complete linear actuator drive unit. It consists of a reversing gerotor gear pump, hydraulic lock valves, suction make-up check valves, a valve housing manifold, an electric permanent magnet motor, an electric solenoid bypass valve and an oil reservoir. Figure 3.
The HRP (Hydraulic Reversing Pumpset) operates as follows: As the motor (1) rotates CCW, oil from the gear pump (2) is pumped towards output “A”. This oil passes through the check valve (5) and goes to the line output (7). The oil pushes the cylinder in the port direction. The pressure at output “A” ensures the check valve (3) stays closed and manually opens check valve (6). Opening check valve (6) allows the returning oil from the steering cylinder to flow back to the pump.
Oil passages are machined as large as possible to minimize any restrictions which may effect manual steering. 3.4 STEERING CYLINDER The brass steering cylinder is engineered and manufactured for heavy duty marine usage and is suitable for commercial and pleasure boat applications. The cylinder has a 1-1/2” bore and a 9” stroke. The trunnion mount (fixed end) and the ball joint allow for about 10 degrees of articulation. The cylinder is shipped full of oil and is also equipped with bleed fittings. 4.
In a new installation, mechanical stops can be installed after the cylinder. For retro-fit applications, use Figure 4.1 as a reference to ensure the ends of the cylinder travel are outside the stops. Mount cylinder with the fittings in the up direction. 4.2 HYDRAULIC The unit is shipped full of oil with a sealed plug in the top of the reservoir cover. A vented breather cap is supplied with the unit. The vented cap must be installed in place of the plug after the drive unit has been mounted.
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6. DRAWINGS 6.1 LA17 ASSEMBLY SCHEMATIC BYPASS VALVE SOLENOID LEADS 6.375” BYPASS VALVE FILLER CAP 5.25” SIDE VIEW MOTOR LEADS 8” 3.
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