Edson Quadrants, Radial Drive Wheels & Tiller Arms — Installation Instructions

Securement Methods (EB-380-2)

• All Edson quadrants, Radial Drive wheels and tiller arms are machined to a -.003" to -.005" clamping tolerance from the rudderpost diameter given with the order. That fit is very tight but will not stop the hub turning under extreme rudder loads: a mechanical fastener must always be used.

Turn the wheel hard over for working room when drilling, and use tapping grease on stainless and metal posts. Contact your boat builder before drilling or modifying a composite or carbon rudder shaft.

What Edson Needs to Machine Yours

• Rudderpost diameter, measured with digital calipers to 0.001" (e.g. 2.375"). Quadrants, radials and tiller arms are custom machined and NON-RETURNABLE.
• Identify an existing quadrant or radial by its “FIG” number (the part number to order); casting numbers marked “PART” refer to only part of it. Otherwise measure from the centre of the bore to the edge: that radius is the size (676-12 = quadrant, 12" radius).
• Securement: key (key stock sold separately in 1/4", 1/2" and 3/8"), through bolt (3/8-inch standard) or set screws (3/8-inch standard, only if key or bolt are not possible). Standard keyways sit at 0° and 180°; non-standard keyways within 20° of 270° and 90° are reviewed before the order is accepted.
• Square rudder posts: give the leg length of the square and how its corners point (points fore and aft at 0° and 180°, or flats fore and aft with the points at 135° and 315°).
• Never attach an autopilot directly to the quadrant or radial drive wheel: use an independent autopilot tiller arm (an “electronic emergency tiller” if the steering gear or a cable fails).

Quadrants (676)

Weights of the 676BR-10 and 676BR-12 are copied as printed (the kg values do not follow the lbs). Quadrants are mostly manganese bronze, radials heat-treated anodized aluminum.

Radial Drive Wheels (777 / 800 / 802)

Radial hub measurements

Distance from the #776AL-4 idler to the radial centre

Minimum distances are for 4" sheaves: add 2" for 6" sheaves. Greater distances are possible: ask Edson.

Autopilot Tiller Arms (EB373-2410)

• Arm height 1 5/8"; open on one side for the autopilot rod end (clevis Part 619 if needed). One 12mm pin is supplied; the installer machines the pin hole once the location is set (pin location per the autopilot maker's specs).
• The autopilot ram MUST sit inside the channel, not above or below it.
• J Boats (aluminum only, potted onto the post, not custom bored): #836AL-J-12 for J/37, J/40, J/42, J/44, J/46, J/105, J/120, J/130; #836AL-J-160 for J/160.
• Call Edson for the 15" large bore arm. The order form asks for material, length, bore, large bore (bore > 3.250in), securement method, autopilot make/model and port or starboard orientation.