AU2010101390A4 - Transom operating mechanism - Google Patents

Description

1 TRANSOM OPERATING MECHANISM FIELD OF THE INVENTION 5 This invention relates to mechanisms for operating transoms attached to the rear of boats and for operating other rotating lifting systems. BACKGROUND OF THE INVENTION 10 AU 2003244607 discloses a hydraulically actuated lift system for mounting to the transom of a boat in which a pair of hydraulic cylinders operate the two arms on which the transom platform is mounted. There is a problem with such systems in that the two cylinders usually do not operate precisely in parallel. 15 The piston of one cylinder will usually extend or contract faster than the piston of the other cylinder and this can lead to jamming of the mechanism and/or damage to the platform. The invention of AU2003244607 attempts to overcome this problem by providing hydraulic fluid conduits between the two cylinders so that fluid is transferred between the two cylinders which results in equal extension or 20 retraction of the pistons of the cylinders. However this solution adds to the already considerable cost of the hydraulic cylinders. Further, any damage to or blockage of the communicating fluid conduits leads to the original problem of non communicating cylinders. 25 OBJECT OF THE INVENTION It is therefore an object of the present invention to provide a transom operating mechanism which overcomes the disadvantages of prior art systems or at least 30 provides a useful alternative.

2 STATEMENT OF THE INVENTION According to the present invention a mechanism to operate a transom platform supported by two or more prime mover arms pivoted to the rear of a 5 boat comprises a rotary actuator which rotates a transverse shaft linked to the arms which raise and lower the platform as the actuator rotates. Preferably the rotary actuator is in line with the shaft and drives it directly. 10 Alternatively the rotary actuator is transverse to the shaft and drives it via a worm gear. Preferably the shaft is linked to the supporting arms by adjustable struts. 15 Preferably the mechanism also has auxiliary arms which together with the prime mover arms form parallelogram linkages to maintain the platform in a level attitude as it is raised and lowered. BRIEF DESCRIPTION OF THE DRAWINGS 20 An embodiment of the invention is now described by way of example only with reference to the accompanying drawings in which: Fig 1 is a perspective view of a transom operating mechanism employing two 25 hydraulic cylinders Fig 2 is a perspective view of a transom operating mechanism employing an hydraulic rotating actuator and Fig 3 is a perspective view of a transom operating mechanism employing a rotating actuator driving a worm gear. 30 3 DETAILED DESCRIPTION OF THE INVENTION In Fig 1 a conventional transom is shown operated by two hydraulic rams 1 linked to arms 2 which are pivoted to the rear of a boat and rotated by rams 1 to raise 5 and lower platform 3. If however, rams 1 operate out of sync arms 2 will apply twisting forces to platform 3 thus causing damage to the platform and/or jamming of the rams. In Fig 2 rams 1 are replaced by rotary actuator 4 which rotates shaft 5 directly. 10 Struts 6 link the rotation of shaft 5 to arms 7 which raise and lower transom platform supports 8. Since struts 6 are passive links they operate in sync when the rotation of actuator 4 raises and lowers the transom platform. The length of struts 6 can also be adjusted to ensure platform 3 is correctly 15 positioned. Auxiliary arms 9 form parallelogram linkages with arms 7 to maintain the transom platform in a level attitude as it is raised and lowered. Fig 3 illustrates an alternative embodiment of the subject invention. Here rotary actuator 10 drives worm gear 11 which rotates shaft 12 which in turn operates 20 struts 13 to raise and lower arms 14. Worm gear 11 allows actuator 10 to be of lower torque than actuator 4 since worm gear 11 increases the torque on shaft 12 whereas there is no gearing advantage of actuator 4 on shaft 5. Auxiliary arms 15 form parallelogram linkages with arms 14 to maintain the transom platform in a level attitude as it is raised and lowered. 25 ADVANTAGES It is obvious that replacing hydraulic rams with an hydraulic actuator overcomes 30 the problem of out-of-sync operation of the rams. Further the combination of an actuator with a worm gear incorporates a mechanical advantage which allows the 4 use of a lower powered actuator which costs significantly less than two hydraulic cylinders which can raise a transom platform. VARIATIONS 5 It will be realized that the foregoing has been given by way of illustrative example only and that all other modifications and variations as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth. Throughout the description and claims of this 10 specification the words "comprise" and variations of that word such as "comprises" and "comprising" are not intended to exclude other additives components integers or steps. 15

Claims (5)

1. A mechanism to operate a transom platform supported by two or more prime mover arms pivoted to the rear of a boat comprising a rotary 5 actuator which rotates a transverse shaft linked to the arms which raise and lower the platform as the actuator rotates.

2. The mechanism of claim 1 in which the rotary actuator is in line with the shaft and drives it directly. 10

3. The mechanism of claim 1 in which the rotary actuator is transverse to the shaft and drives it via a worm gear.

4. The mechanism of claim 1 in which the shaft is linked to the arms by 15 adjustable struts.

5. The mechanism of claim 1 which also has auxiliary arms which together with the prime mover arms form parallelogram linkages which maintain the platform in a level attitude as it is raised and lowered. 20 25