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Critical Compression Buckling Load, Critical Resonance Speed, Overheating and Lateral Load of a Screw Jack

CRITICAL COMPRESSION BUCKLING LOAD OF A SCREW JACK: When there are compression loads on the screw, it may fail due to buckling, before reaching its static load capacity. If the critical compression buckling load calculated is lower than the actual compression buckling load applied, a screw jack with a larger diameter screw must be selected and its suitability checked. In general, the load applied on the screw jack, including possible impacts, must not surpass the calculated value. The safety factor considered is 3; reconsider this if so considered opportune for the specific application. As a recommendation, when a hypothetical screw jack failure may involve injuries to people, multiply the critical load calculated by an additional factor of 0.6.

* Malaysia customer four 10-ton jacks and four P140 gearboxes for motorized worm gear screw lift table Video: https://www.youtube.com/watch?v=z_GpDOLi6Ek
* Pakistan customer acme screw lift motorized 25t capacity 500mm stroke motorized screw jack actuators Video: https://www.youtube.com/watch?v=5olVMY162SQ&t=10s
* Australia customer SEVEN 1-ton jacks in-line electric jack screw lift tables Video: https://www.youtube.com/watch?v=RDqjjY9MYNk
* Australia customer SEVEN 5-ton screw jacks Inline T-configurations for motorised screw jack system Video: https://www.youtube.com/watch?v=lBGnafTbOFI
* Philippines customer 2.5 ton upright screw jacks with customized rect. top plate(flange) 200 mm lift Video: https://www.youtube.com/watch?v=2WraD7L--hQ&t=36s
* USA REGULAR customer inverted 5 ton machine screw jacks 4" stroke 24:1 ratio with top plate end Video: https://www.youtube.com/watch?v=xufGOAqCy88&t=31s
* Australia REGULAR customer sluice gate screw jack 2.5 ton capacity SS304 lift screw 1000 mm stroke Video: https://www.youtube.com/watch?v=bkmexMs8duA&t=27s
* Chile REGULAR customer 2.5 ton worm screw jack lifting systems 200 mm travel and 1:1 ratio gearbox Video: https://www.youtube.com/watch?v=Fluo9YMcGbo&t=41s
* Thailand customer 50 ton heavy duty screw jacks 120 mm dia. lifting screw 800 mm stroke Video: https://www.youtube.com/watch?v=7-yw-LyjP-Q&t=33s
* Sri Lanka REGULAR customer 5 ton Inverted electric worm gear screw jack 500 mm stroke and clevis end Video: https://www.youtube.com/watch?v=rpCUtW0QM4Q
* Malaysia customer 35 ton machine screw jack system with accessories (gearboxes, couplings, shafts) Video: https://www.youtube.com/watch?v=gpsLAkBuVa0&t=50s
* Argentina Customers Inverted 5 ton and 2.5 ton rotating nut screw jacks with stainless steel screws Video: https://www.youtube.com/watch?v=KX21dDbD_EM&t=16s
* UAE import JACTON Upright 5 Ton Manual Jack Screw Actuator Top Plate 300 MM Stroke with Handwheel Video: https://www.youtube.com/watch?v=pLfybelp66U
* USA client hand crank table raising mechanism 2.5 ton, mechanical linkage hand crank jacks for desk Video: https://www.youtube.com/watch?v=eFc880t92IY
* Australia motorized electric screw jack actuators 15 ton, motorized worm gear screw jack Video: https://www.youtube.com/watch?v=Jxomq5j7_FM
* US client 2.5ton screw mechanism for manual table lift, table lift with crank mechanism, crank jacks Video: https://www.youtube.com/watch?v=5B4s0miJZA0
* Australia customers inverted rotating screw jack systems with travelling nut 1500 mm 2.5 tonnes Video: https://www.youtube.com/watch?v=qcqFQ4_WOPE&t=12s
* South Africa customer inverted 10 ton screw jack with 220v single phase geared motor 600 mm stroke Video: https://www.youtube.com/watch?v=Yit-sr59dHg&t=17s
* Vietnam customer 25 ton heavy duty screw jacks 500 mm custom rod dia. 90 mm 80:1 and 10-2/3:1 ratio Video: https://www.youtube.com/watch?v=T1iz_rRhe4c
* Philippines customer anti-rotation keyed 5 ton screw jacks with customized rect. top plate(flange) Video: https://www.youtube.com/watch?v=uqBhthAoHuQ&t=32s
* India customer 2.5T rotating screw jack stroke 600mm 24:1 ratio double input shafts or motor flange Video: https://www.youtube.com/watch?v=Drx6fPS0JZE
* Belarus REGULAR customer 5 ton electric screw jack with 1.1 kw 6pole motor 200 mm stroke 24:1 ratio Video: https://www.youtube.com/watch?v=NfrHzgqqbjA&t=52s
* Vietnam customer Customized 10 ton rotating screw jack without travel nut also without thread screw Video: https://www.youtube.com/watch?v=VONw-x-iwHE&t=4s
* Italy NEW customer quality 1-ton handwheel screw jacks 300 mm stroke with fast delivery time Video: https://www.youtube.com/watch?v=ASzjA4EF0Xw
* Philippines customer customize upright mechanical screw jacks 50:1 reduction ratio 300 mm stroke Video: https://www.youtube.com/watch?v=Zn-z26abW9E
* America customer 2.5 tons screw jack for work table adjustment/motorised power the lifting systems Video: https://www.youtube.com/watch?v=qWQF1nEPQ-c&t=1s
* Australia customer 5 tons powered long travel screw jacks/long stroke worm gear/long jack screws Video: https://www.youtube.com/watch?v=cZMoEihf9Y8&t=3s
CRITICAL RESONANCE SPEED OF A SCREW JACK: Applicable to the TRAVELLING NUT SCREW JACKS version (the screw rotates and the nut moves). With reduced diameter and long length screws, there is a risk of having considerable vibration on turning if this occurs at speeds close to the first vibration frequency (the second and highest correspond to very high speeds, at which the screws never work). In the worst cases, the screw may break and, additionally, the risk of collapse due to side buckling considerably increases. For these reasons, be sure that the screw jack screw works at considerably lower rotation speeds than resonance speeds. If not, select a screw of a larger diameter and/or reduce its turning speed and/or modify the screw jack end supports.
 
OVERHEATING OF A SCREW JACK: With the aim of avoiding overheating due to internal friction of the screw jacks, the axial strength and the advance speed must be controlled. To do this, check the unit selected. If it does not comply, choose a larger screw jack and/or reduce the load and/or reduce the speed. For very small strokes, please contact the NIASA technical department.
 
LATERAL LOAD OF A SCREW JACK: JACTON recommends that, if they exist, the lateral loads on the screw must be supported by guide systems designed for this purpose, in addition to the guide for the gearbox, so that the screw or the nut exclusively support axial traction/ compression loads. If there are side loads, the life of the screw jack will be notably reduced, as there will be premature wear of the screw and the nut, which is often the origin of faults.