Shaft contact device
The invention relates to a shaft contact device 1 to make an electrical connection between a shaft and an earth point. Device 1 has a bracket 10 for connection to a point spaced from the rotating shaft, base member 20 mounted on the bracket 10 , a head member 30 having at least one electrically conductive brush 34 A, 34 B to engage the shaft. A pair of arms 40 A, 40 B each has a first end connected to spaced pivot points on the base member and a second end connected to spaced pivot points on the head member. A spring means 50 biases the head towards the shaft to engage the brush on the shaft. In use the base member, head member and spaced arms forming a parallelogram arm whereby the head member brushes contact the shaft at a constant angle as the brushes are worn.
1 . A shaft contact device to make an electrical connection between a rotating shaft and an earth point comprising:
a bracket for connection to a point spaced from the rotating shaft;
a base member mounted on the bracket;
a head member having at least one electrically conductive brush to engage the rotating shaft;
a pair of arms each having a first end connected to spaced pivot points on the base member and a second end connected to spaced pivot points on the head member, and
a spring means to bias the head towards the rotating shaft to engage the at least one electrically conductive brush on the rotating shaft, in use the base member, head member and spaced arms forming a parallelogram arm whereby the at least one electrically conductive brush of the head member contacts the rotating shaft at a constant angle as the at least one electrically conductive brush is worn.
2 . The shaft contact device according to claim 1 , wherein the bracket is adapted to be mounted on a connection point through which the rotating shaft extends.
3 . The shaft contact device according to claim 1 , wherein the bracket is connected to a connection point using one or more cable ties.
4 . The shaft contact device according to claim 3 , wherein slots are provided on the bracket to accommodate the one or more cable ties.
5 . The shaft contact device according to claim 1 , wherein the bracket is of plastics and heat deformable to adjust its shape to lie adjacent different shapes at the spaced point to which it is to be attached.
6 . The shaft contact device according to claim 1 , wherein the spring means spans opposing corners of a parallelogram defined by the arms and the spaced pivot points.
7 . The shaft contact device according to claim 1 , wherein the arms have elongate recesses to accommodate the spring means when the arms come together adjacent each other.
8 . The shaft contact device according to claim 1 , wherein the at least one electrically conductive brush are wired to a terminal to connect with a wire leading to an earth point anode or cathode.
9 . The shaft contact device according to claim 1 , wherein the head includes an electrically conductive contact member adjacent the base member of the at least one electrically conductive brush which engages the rotating shaft when the brushes become worn.
10 . The shaft contact device according to claim 9 , wherein an alarm circuit is provided to generate an alarm when the contact member engages the rotating shaft to indicate that the at least one electrically conductive brush needs replacing.
11 . The shaft contact device according to claim 8 , wherein an alarm circuit is provided to operate an alarm if water is present between an electrically conductive contact member and the terminal to indicate that a seal around the rotating shaft is leaking.
12 . The shaft contact device according to claim 1 , wherein the first and/or second ends of the arms are adapted to be connected to one of a number of spaced pivot points to adjust the constant angle of the head member relative to the base member.
13 . A marine engine with a prop shaft or drive shaft, incorporating the shaft contact device according to claim 1 .
14 . A system which includes the shaft contact device according to claim 8 and an alarm circuit which is operatively connected to a wireless transmitter which in use transmits an alert signal to a remote location upon receipt of a signal from a sensor.
15 . The system according to claim 14 wherein the sensor detects that the at least one electrically conductive brush is worn.
16 . The system according to claim 15 wherein a wireless receiver is configured to receive the alert signal and to display or relay a warning to indicate that the at least one electrically conductive brush is worn.
17 . The system according to claim 15 wherein the sensor detects a variation in an electrical characteristic to indicate that the at least one electrically conductive brush is worn.
18 . The system according to claim 15 wherein the sensor detects a variation in a mechanical characteristic to indicate that the at least one electrically conductive brush is worn.
19 . The system according to claim 11 wherein a sensor detects if water is present between the electrically conductive contact member and the terminal or in a bilge to indicate if there is leakage between the rotating shaft and shaft seal.
20 . A marine craft or vessel including the device according to claim 1 .
21 . A marine craft or vessel including the marine engine according to claim 13 .
22 . A marine craft or vessel including the system according to claim 14 .