- 1 Electromagnetic Brake Field of the Invention 5 This invention relates to an electromagnetic brake, in particular an electromagnetic brake for a golf buggy. Background 10 Golf buggies that are electrically controlled enable a user to drive the golf buggy rather than having to pull the golf along behind them (or push the golf buggy in front of them). The use of the term "golf buggy" refers to 15 golf buggy's capable of carrying golf club bag so that a player does not need to carry the golf club bag them self (a push/pull golf buggy). The term "golf buggy" is not intended to refer to a ride on golf buggy that also serves the purpose of carrying a golf club bag. 20 A problem with electrically controlled golf buggies is that when they are stopped on uphill/downhill sections of a golf course the weight of the buggy and the clubs can cause the buggy to roll down the hill. Some golf buggies 25 are fitted with a foot brake that can be manually operated by a user to clamp the wheels, however these brakes can be cumbersome and a hassle to consistently use. The present invention was conceived with the above problem 30 in mind. Summary of the Invention 35 The invention provides an electric golf buggy comprising: a wheel; an electric motor having a drive shaft that drives the wheel, the drive shaft having a brake shoe 5891922_1 (GHMatters) P98348.AU AJFW 15/12/14 - 2 coupled to the drive shaft; and an electromagnetic brake associated with the electric motor, the electromagnetic brake having an electromagnetic coil and a plate, the electromagnetic coil attracting the plate towards the 5 electromagnetic coil when the electromagnetic brake is activated; wherein when the electromagnetic brake is activated the plate engages the brake shoe to restrict the drive shaft from rotating. 10 By having an electromagnetic brake that engages a brake shoe when activated, a user can easily and reliably restrict the drive shaft from rotating. In some embodiments of the invention the electromagnetic 15 brake comprises a brake housing, wherein when the electromagnetic brake is activated the brake shoe is clamped between the plate and the brake housing. In some embodiments the electromagnetic brake further 20 comprises a spring to bias the plate away from the electromagnetic coil. By providing a spring to bias the plate away from the electromagnetic coil it is possible to ensure that the 25 brake shoe is able to rotate freely when the electromagnetic brake is not activated. In some embodiments the motor and the electromagnetic brake are contained within a single housing. Housing the 30 electromagnetic brake and the motor in a single housing allows for a more compact design. Brief Description of the Drawings 35 An embodiment, incorporating all aspects of the invention, will now be described by way of example only with 5891922_1 (GHMatters) P98348.AU AJFW 15/12/14 - 3 reference to the accompanying drawings in which; Figure 1 is a sectional view of a drive system of an electric golf buggy including an electromagnetic brake; 5 and Figure 2 is an enlarged sectional view of the electromagnetic brake in Figure 1. 10 Detailed Description of an Embodiment of the Invention Referring to Figure 1, a drive system 1 of an electric golf buggy is shown. The drive system has a housing 2 15 comprising a cylindrical housing 3 with open end caps 4,5. Inside the main housing is an electric motor 10. The electric motor 10 has a rotor 11 and a stator 12. The stator 12 is fixed to the cylindrical housing 3 and the rotor 11 is free to rotate within the stator 12. The rotor 20 11 is connected to a driveshaft, shown as motor shaft 20. The motor shaft 20 drives a worm gear 21 which in turn drives one or more wheels of an electric golf buggy (not shown). 25 One of the end caps, end cap 4, has a bearing 6 that supports the motor shaft 20 at a first end 22 of the motor shaft 20. The end cap 4 has an opening that allows the motor shaft 20 to extend through to the outside of the housing 2. The end cap 4 has a motor input line 8 that 30 supplies current to drive the electric motor 10. When power is supplied to the electric motor 10 the rotor 11 rotates inside the stator 12 and drives the motor shaft 20. 35 The other end cap, end cap 5, has a bearing 7 that supports the motor shaft 20 at a second end 23 of the 5891922_1 (GHMatters) P98348.AU AJFW 15/12/14 - 4 motor shaft 20. Attached to the end cap 5 is an electromagnetic brake 30. The electromagnetic brake 30 is mounted to the end cap 5 such that the motor shaft 20 extends through the electromagnetic brake 30. The 5 electromagnetic brake 30 is capable of being engaged in order to prevent the motor shaft 20 from rotating. The end cap 5 has an electromagnetic input line 9 that supplies current to the electromagnetic brake 30. In this way the motor 10 and the electromagnetic brake 30 are contained 10 within a single housing (housing 2). The electromagnetic brake 30 comprises a brake housing 35, an electromagnetic coil 31 and a plate 40. The electromagnetic coil is secured to the brake housing 35. 15 The plate 40 is a flat annular disk with a central hole 41 through which the motor shaft 20 extends. The plate 40 is attached to the brake housing 35 by three equally spaced bolts 50 that extend through three securing holes 42 in the plate 40. The bolts also attach the brake housing 35 20 to the end cap 5. Sleeves 51 around the bolts 50 allow the plate 40 to move axially relative to the motor shaft 20. Three equally spaced springs 33 bias the plate 40 away from the brake housing 35. The ends 52 of the sleeves 51 act to retain the plate 40. The springs are located in 25 holes 36 in the brake housing 35. The plate 40 is made from metal, preferably a ferrous metal, and more preferably iron. It will be understood that the plate 40 could have four 30 equally spaced bolts that extend through four securing holes in the plate. It will be further understood that the plate 40 could be designed to have five or more equally spaced bolts and corresponding holes. 35 The electromagnetic brake 30 also comprises brake shoe 34. The brake shoe 34 is located in a recess 37 in the brake housing 35, and is attached to the motor shaft 20 by a pin 5891922_1 (GHMatters) P98348.AU AJFW 15/12/14 - 5 24 that is located towards a second end 23 of the motor shaft 20. The brake shoe 34 is free to rotate within the recess 37 of the brake housing 35, with the motor shaft 20, when the electromagnetic brake 30 is disengaged. 5 When the electromagnetic coil 31 is activated it generates a magnetic field that attracts the plate 40. The magnetic attraction of the plate 40 to the electromagnetic coil 31 causes that plate to be axially displaced towards the 10 electromagnetic coil 31, overcoming the bias of the springs 33. The axial displacement of the plate 40 towards the electromagnetic coil 31, and thereby also the brake housing 35, causes the plate 40 to contact the brake shoe 34 and clamp the brake shoe 34 between the brake housing 15 35 and the plate 40. The frictional force generated between the plate 40 and the brake housing 35 restricts the brake shoe 34 from rotating, and as a result the motor shaft 20. 20 The brake shoe 34 is made from a friction material conventionally used in the brake and motor industry. The brake shoe 34 may be made from an aluminium alloy, however if a larger braking force is required a material with a greater coefficient of friction may be used. 25 The brake shoe 34 provides a large surface for the plate 40 to clamp down on, rather than clamping the motor shaft 20 directly. This allows the plate 40 to have a good frictional engagement with the brake shoe 34. 30 It will be understood that the brake shoe 34 does not need to be connected to the motor shaft 20 by a pin 24, as described above. For example, the motor shaft 20 may be connected to the brake shoe by any suitable key and keyway 35 setup. The motor input line 8 and the electromagnetic input line 5891922_1 (GHMatters) P98348.AU AJFW 15/12/14 - 6 9 are connected to controlling circuits which control when power is supplied to the electric motor 10 and the electromagnetic brake 30. When the electric buggy is directed to move forward the controlling circuits supply 5 current down the motor input line 8, which supplies power to the motor 10. In addition, controlling circuits do not supply current to the electromagnetic input line, resulting in the spring 33 biasing the plate 40 away from the electromagnetic coil 31, thereby disengaging the 10 electromagnetic brake 30 and allowing the brake shoe 34 to rotate freely. When the buggy is directed to stop the controlling circuits cut power supply to the motor input line 8 and 15 therefore the electric motor 10, causing the motor 10 to drive the wheels of the buggy. The motor itself, when not being supplied power, acts as a brake for the buggy. The electromagnetic brake 30 can then be engaged either automatically or selectively. If the electromagnetic brake 20 30 is engaged automatically then when power is cut to the motor input line 8 the controlling circuits automatically supply power through the electromagnetic input line 9 to the electromagnetic coil 31. This causes the electromagnetic coil 31 to be energised and produce a 25 magnetic field. The magnetic field attracts the plate 40 and overcomes the bias force from the springs 33, resulting in the brake shoe 34 being firmly held between the plate 40 and the housing 35, and preventing the brake shoe 34 from rotating. 30 Alternatively, the electromagnetic brake 30 may be engaged selectively by a user. For example, the user could push a button in order to selectively engage the electromagnetic brake 30. 35 Having an electromagnetic brake is beneficial when the buggy stops on a hill, for example an uphill or a downhill 5891922_1 (GHMatters) P98348.AU AJFW 15/12/14 on a golf course, as it prevents the buggy from rolling down the hill. By clamping the brake shoe 34 between the plate 40 and the brake housing 35 the buggy's whole drive chain is restricted from rotating, which prevents the 5 electric buggy for moving under its own weight (i.e. gravity), thereby allowing the buggy to reliably stop in the position that the user desires. The worm gear 21 may drive one or more wheels. The worm 10 gear 21 will normally drive two wheels, typically the two rear wheels, with one or more front wheels used to steer the golf buggy. In order to help facilitate the golf buggy turning there may be a differential between the worm gear 21 and the driven wheels. 15 It will be understood that it would be possible to have a golf buggy that had two electric motors, with each motor driving one of the rear wheels. In this instance it would be possible to have an electromagnetic brake on both of 20 the motors or, alternatively, only have an electromagnetic brake on one of the motors. It is envisaged that the electromagnetic brake will reliably stop the buggy's drive system from rotating on up 25 hills or down hills that are inclined/declined less than or equal to approximately 16' from horizontal. In the claims which follow and in the preceding description of the invention, except where the context 30 requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further 35 features in various embodiments of the invention. 5891922_1 (GHMatters) P98348.AU AJFW 15/12/14