Selden Hydraulic Assembly (Power Pack) — Owner's Manual

Power Pacs & Valve Blocks

Discontinued model — documents and spare parts as printed.

• A complete system: pump with motor and reservoir, valve block with a directional valve per function, and a control box. 12 and 24 volt versions. Designed for intermittent use, not continuous operation.
• Single power pac: cylindrical tank, one function at a time, own return-line filter. Boom outhaul together with a furling motor needs two single units.
• Double power pac (24 V only): two pumps in a rectangular tank with a built-in common return filter. Runs two functions at once, or both pumps in parallel for double flow to one large function (then add a single unit for a boom outhaul). Run individually, the left pump (1) drives the boom outhaul and the right pump (2) the Furlex etc.
• Valve block for motors: 2- or 3-function, aluminium with cartridge valves; blocks can be combined for more functions. Valve block for the boom outhaul: adds an overcentre valve that holds outhaul pressure after the pump stops.
• Below-deck hoses are optional; hoses from the application (e.g. furling mast motor) to the deck gland come with that application.

Assembly by Installation

OML 12.5, OMM20 etc. give the hydraulic motor size. Hose set: keel-stepped / deck-stepped mast. XXX = not available.

Checklist per installation: power pac(s) (check 12/24V; one filter unit per single pac, built-in filter on the double), valve unit(s) for motors and / or boom outhaul, four dampers per power pac incl. 8 M8 nuts & washers, control box with 2 relays per function, manual 595-922-E.

Installation

• Both electrical and hydraulic systems should be professionally installed. Protect all units from moisture and physical damage; give the power pac ventilation (the motor gets hot) and access for oil, filter and pressure valve.
• Buttons: mount the two OUT buttons together and the two IN buttons together (e.g. pedestal: OUT starboard, IN port) – outhaul and furling mast are separate systems run together.
• Control box: close to the valve unit, fed from the panel via switch and fuses; height including lid = 100 mm; changeover switch set to separate on installation.
• Single pac: steel tank, horizontal (fore and aft) or vertical; max recommended fill 9 litres (9.5 litres horizontal); drain plug diagonally opposite the filler. Double pac: aluminium tank on four rubber pads with M8 screws, max 14 litres; filter, filler, dipstick and venting-hose connection on top.
• Fit the venting hose (roughly 0.6 m) to discharge as high above the tank as possible, with no water trap. Use the rubber pads to cut noise.
• Motor cable: crimp terminals for M8 screws. Minimum cable area 50 mm2 (12V) / 35 mm2 (24V).
• Single-pac filter: spin-on, on the return line; two M8 holes (cc40mm); note the flow arrows.
• Hoses below deck (optional): min bend radius 125 mm for 3/8" hose, 175 mm for ½". Never twist a hose – 25° of twist cuts its life by 90%. Clip hoses every 400-500 mm with rubber clips, keep them off sharp edges, plug all open ends. If buying hoses elsewhere, use SAE 100R7/DIN 24951. If a length is hard to measure, order the hose slightly long with one end open and have it crimped locally.
• Never run the assembly without oil in the tank.

Cable sizing

Lmax = (cable area × voltage drop) / (0.017 × current), where Lmax = positive + negative cable length battery – pump (m), voltage drop 0.6V (12V) / 1.2V (24V) = 5%, 0.017 for copper.

Pressure Relief & Valve Settings

• Each manifold carries a manometer and a pressure relief (system / working pressure) valve. If load rises too far (e.g. furling the genoa without easing the sheet) it opens and returns oil to the tank.
• Boom outhaul unit: relief valve set to between 100 and 160 bar depending on boom size; adjustment is in the boom outhaul manual 595-091.
• Motor unit (Furlex etc): must always be set to 140 bar. At 140 bar the pac runs 3-5 minutes before the motor thermal cut-out trips (resets automatically when cool); in heavy weather furling can reach 130-140 bar. Let the motor cool between furling operations.
• Furling-mast port relief valve (5): RC and RD set to max (140 bar working pressure); RB set to 120 bar. To change it: hold screw (b), loosen nut (a); anti-clockwise reduces, clockwise increases; re-lock. There is no manometer on this valve – check at the A- or B-port, e.g. with a gauge on the mast-motor quick coupling.
• Flow control valves (motor block, 1–4): delivered at maximum. Hold screw (b), loosen nut (a); clockwise reduces flow, counter-clockwise increases. Heavy restriction causes high power losses. Built-in check valve lets oil return freely.
• Directional valves have LED-lit solenoids and manual buttons at each end to release residual pressure. Boom outhaul valves: overcentre 33.2, flow control 34.1 & 34.2 (optional), emergency 35 (red knob, clockwise closed, hand-tight), non-return 33.1 (do not adjust).

Setting the 140 bar relief valve (motor unit)

1. Disconnect the Furlex1 hose quick couplings at the deck gland and cap them.
2. Press FURLEX IN for 2 to 3 seconds – all oil goes over the relief valve.
3. One person reads the manometer while another presses the button.
4. Remove cap nut (1) of adjusting screw (2) (a little oil may leak; sealing washer 3) and loosen locking nut (4).
5. Adjust: clockwise (+) increases, anti-clockwise (-) decreases. If too high from the start, back off a few turns, re-test, then come up to the value.
6. Tighten locking nut (4), refit sealing washer (3) and cap nut (1) to seal.
7. Re-check on the manometer.
8. Reconnect Furlex1 at the deck gland.

A higher relief setting means a higher maximum current, which sets the cable size.

12 or 24 Volts on Board?

Selden recommends 24 volt DC for hydraulic rig systems because reefing large sails needs a lot of power. Example: a 40 to 50-foot boat's hydraulic pump has a 3-kilowatt motor; P = U x I, so at 3,000W the current is 250 amperes at 12 volts but 125 amperes at 24 volts. High current is a safety risk – have a trained technician install it.