ActionJac™ Worm Gear Jack systems 2016 by NOOK Industries

More catalogs by NOOK Industries | ActionJac™ Worm Gear Jack systems 2016 | 110 pages | 2016-08-25


Page 10 of ActionJac™ Worm Gear Jack systems 2016

for multiple jack arrangements total horsepower required depends on horsepower per jack number of jacks the efficiency of the gear boxes and the efficiency of the arrangement to use the charts pages 30 68 102 122 140 158 and 159 find a point at which the maximum length “l” intersects the maximum load be sure the jack selected is above and to the right of that point arrangement efficiency – maximum length – the maximum length includes travel housing length starting/stopping distance extra length for boots and length to accommodate attachment of the load • two jacks 95 • three jacks 90 • four jacks 85 • six to eight jacks 80 the efficiency of each miter gearbox is 90 therefore motor horsepower requirement for the arrangement horsepower arrangement hp per jack × number of jacks arrangement efficiency × gearbox efficiency n where n number of gearboxes do not exceed the maximum allowable input horsepower for a jack many models cannot lift the full rated load at 1,800 rpm if the horsepower required exceeds the maximum value for the jack selected several solutions are possible • use a larger jack model to increase the maximum allowable horsepower • use a ball screw jack to reduce the power required to do the same work • operate at a lower input speed • use a right angle reducer to bring the power requirement within acceptable limits when utilizing multiple jack arrangements the input torque to the first jack must be considered it is recommended that the number of jacks driven through a single jack input be limited to a maximum of three jacks consult nook application engineers for arrangements where more than three jacks will be driven through a single jack input if column strength is exceeded for the jack selected consider the following options • change the jack configuration to put the lift shaft in tension • increase size of jack • add a bearing mount like the ezze-mount™ for rotating jacks • change the lift shaft mounting condition e.g from clevis to top plate caution chart does not include a design factor the charts assume proper jack alignment with no bending loads on the screw effects from side loading are not included in this chart jacks operating horizontally with long lift shafts can experience bending from the weight of the screw critical speed the speed that excites the natural frequency of the screw is referred to as the critical speed resonance at the natural frequency of the screw will occur regardless of the screw orientation or configurations of the jack vertical horizontal translating rotating etc the critical speed will vary with the diameter unsupported length end fixity and rpm of the screw since critical speed can also be affected by the shaft straightness and assembly alignment it is recommended that the maximum speed be limited to 80 of the calculated critical speed column strength because of the nature of most screw jack applications critical speed is often overlooked however with longer travels critical speed should be a major factor in determining the appropriate size jack refer to nook industries precision screw assemblies design guide to best determine the appropriate critical speed for a particular jack selection column strength is the ability of the lift shaft to hold compressive loads without buckling with longer screw lengths column strength can be substantially lower than nominal jack capacity travel rate – establishing a travel rate allows for evaluation of critical speed and horsepower limits acceleration/deceleration time needs to be considered when determining maximum required travel rate if the lift shaft is in tension only the screw jack travel is limited by the available screw material or by the critical speed of the screw refer to the acme screw and ball screw technical sections for critical speed limitations if there is any possibility for the lift shaft to go into compression the application should be sized for sufficient column strength type of guidance charts are provided in each section to determine the required jack size in applications where the lift shaft is loaded in compression brakemotor sizing required application data safety is the most important consideration a brake motor is recommended for all actionjac™ products where there is a possibility of injury load only 20:1 or greater ratio machine screw jacks can be considered self-locking in the absence of vibration the horsepower requirements determine the size of the motor upon selecting a brake motor verify that the standard brake has sufficient torque to both hold the load and stop the load caution high lead ball screw jacks may require larger nonstandard brakes to stop the load an appropriately sized brake will insure against excessive “drift” when stopping for both the ball screw and machine screw jacks a major benefit of the use of ball screw jacks is the ability to predict the theoretical life of the ball screw ball screw life charts are located at the beginning of each ball screw jack section pages 28 -29 121 and 160 finishes gear box housing finish 1⁄2 ton mj 1 ton aluminum industrial enamel paint ductal cast iron industrial enamel paint 300 series casting unpainted aluminum clear anodize ss jacks cubic jacks total maximum thrust load on jacks total maximum thrust load on any one jack number of jacks travel • • inches orientation vertical horizontal arc diagonal etc travel rate • • • optimal speed minimal acceptable speed maximum acceptable speed duty cycle ball screw life 2 ton 100 ton • • • introduction worm gear screw jacks design considerations continued per customer request we can apply epoxy paint or mil specification primers and paints or paint to other special requirements • • • • distance per cycle number of cycles per time period maximum distance traveled in any year life desired configuration • • • tension compression or both driven by hand motor or other translating rotating or double clevis arrangement • arrangement type h t u inline • arrangement dimensions x y1 y2 etc for dimension information please refer to the guides online at www linear motion systems require both thrust and guidance jacks are designed to provide thrust only and provide insufficient guidance support the guidance system must be designed to absorb all loads other than thrust nook industries can provide either hardened ground round shafting or square profile rail to support and guide linear motion systems nook worm gear screw jacks are used widely in tire manufacturing 16 nook precision actuators the specifications and data in this publication are believed to be accurate and reliable however it is the responsibility of the product user to determine the suitability of nook industries products for a specific application while defective products will be replaced without charge if promptly returned no liability is assumed beyond such replacement 17