The Shaft Brush (shaft wiper) is one of the more important elements in a boats bonding system.
A common theory is, the shaft is attached to the engine and the engine is wired into the bonding system, therefore the shaft and propeller are protected by the vessels main zinc corrosion control scheme.
The actual fact is the shaft connection to the engine is interrupted by the oil in the reduction gear.
The Shaft Brush will provide a low resistance connection between the bonding system and the shaft. This connection should allow a properly sized and installed zinc corrosion control system to provide an adequate protection to the shaft and propeller. See the propeller shaft slip ring system at the bottom of this page.
On twin screw installation you will need to install a Shaft Brush on each shaft. Larger shafts and or props may require special systems that will allow the higher current required for the surface area to be protected.
An additional benefit is that zinc installed onto the shaft, will last somewhat longer. After the propeller shaft zinc is consumed, additional protection is then provided by the vessels main zinc corrosion control scheme.
There are currently 4 types of "Shaft Brushes" available. Each design has its advantages. The primary advantage is the current carrying capacity. Obviously the larger and longer the exposed shaft is and as the surface area of the propeller increases the current capacity of the shaft brush must be increased.
The three lower amperage models use self lubricating bronze contacts. The higher amperage unit is called a slip ring assembly. this unit includes silver bands for the shaft surface and silver alloy brushes for the contacts.
Standard, low amperage bronze contact: Part Number ELESB6B
Heavy Duty bronze contact: Part Number ELEHDSB
Highest Amperage bronze contact type: Part Number BOASB
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EXPLANATION OF NUMBERED ITEMS |
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| 1 | Precision calibrated tensioning SS spring |
| 2 | Stainless steel band |
| 3 | Self lubricating bronze contacts - Adjustable to shaft diameter |
| 4 | Shaft - acceptable diameters are 1" to 3 1/4" |
High Amperage slip ring type:
| Electro-Guard propeller shaft slip ring assemblies have been designed to provide a very low resistance electrical contact to the boat's propellers and shafts. These devices are made necessary by the fact that electrical continuity through a marine transmission to the propeller shaft is typically quite poor. | |||||||||
| The
slip ring bands are made of Sterling Silver and the brushes are composed of
an 85 percent silver alloy. The brushes are spring loaded to maintain the
proper contact against the slip rings. Each Electro-Guard slip ring assembly is built to fit the specific shaft diameter of the vessel on which it will be installed. It is necessary, therefore, that an accurate diameter dimension of the propeller shafts) be provided to us when placing an order - the shaft should be measured with a micrometer caliper. |
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We also require the length of the exposed wetted surface of each propeller
shaft and a geometrical representation of each propeller with dimensions
so that we can calculate the total wetted surface of each propeller and
shaft assembly. If an E.A.R. number is known for a particular propeller,
that number and the propeller diameter is sufficient for us to calculate
its surface area.
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| We will provide a form upon request that will assist you in providing this
information. Simply request our Vessel Data Acquisition Form (VDAF) and
provide us with your fax phone number. We will fax the form to you.
After you have filled in the appropriate information and faxed it back, we will send our recommendations with a price quotation for the slip ring assemblies. There is no charge for this service. Electro-Guard propeller shaft slip rings provide superior electrical contact to a boat's propellers and shafts, and have proven themselves in hundreds of installations over the past eight years.
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Pricing for Slip Ring Assemblies are by quote only - but
estimated
pricing is:
2" shaft Call for quote
3" shaft Call for quote
Request for Additional
Information
For current pricing of any item that has a price listed on our web site, get
a quote. Prices are estimated and are not guaranteed to be accurate and may
change without notice or obligation.
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Model 902 Corrosion Test Instrument Kit |
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Use the 902 Test Instrument to:
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902 Instrument Kit Includes:
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| Fluke Model 70 digital multimeter with test leads - protective plastic carrying case with compartments for test probes and leads (case floats) - Zinc reference probe with 20' of test lead wire - a 25' test lead extension - a hardened steel test probe - instructions for the multimeter and for corrosion testing | ||||||||