SU1283517A1 - Screw jack - Google Patents

Abstract

The invention relates to a device for lifting goods. The purpose of the invention is to provide an automatic change in the speed of movement of the rod during the forward and reverse course depending on the magnitude of the load. The screw jack includes a housing 1, a retractable rod 3, a nut 5, a screw 8, which is able to move under the action of a load in the axial direction by means of a disc spring 15. The tray 14 spring serves to press the bearing 9. Rotation on the screw 8 is transmitted from the shaft 18 through two speed gearbox. When the axial load on the screw 8 appears, the screw moves, compressing the spring 15 until the bearing 9 stops against the collar of the gearbox 2. Moving the screw 8 causes the two arms 20 to rotate, while the coupling 21, moving along the splines of the shaft 18, turns off the overdrive in the two-speed the gearbox, and then under the action of the springs includes a lower gear. 3 il. i SL

Description

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This invention relates to lifting devices.

The purpose of the invention is to improve the performance characteristics by automatically changing the rate of stem advance during forward and reverse stroke, depending on the magnitude of the load acting on it.

Figure 1 shows the screw jack

general form; figure 2 - section aa in Fig, 1; Fig. 3 shows the position of the shift lever depending on the position of the screw of the jack.

Screw jack includes a housing 1. (Fig.1) n crankcase 2 gear, fastened together. In the cavity of the housing 1 is installed a hollow retractable, rod 3 with a ball support fixed to the end 4. On the other

the end of the sliding rod 4 is fixed cargo nut 5. On the sliding rod 3 there is a key groove 6, into which is inserted a protrusion of a key 7 fixed to the body and fixing the sliding rod 3 from turning. The thread nut of the cargo nut 5 encompasses the screw thread 8. On the latter, a double thrust ball bearing 9 is seated, the tight ring of which is pressed against the screw flange through the sleeve 10 by the gear cylindrical wheels 11 and 12, which in turn are pressed by the nut 13. Gear cylindrical wheels 11 and 12 are rigidly mounted on the driven shaft connected to the screw. The loose bearing rings are clamped by the cup springs 14 and 13, which are installed in the recesses of the housing 1 and the crankcase 2 of the gearbox. The spring 15 is designed for a higher load, as a result of which the spring 14 sinks into the recess of the housing 1, and the corresponding free ring of the ball bearing 9 rests against the shoulder of the housing 1. In this case there is a gap between the other free bearing ring 9 and the collar 2. The screw 8 is installed in the gearbox housing by means of the toothed spur wheel 12, which is supported through the needle bearing 16 on the centering lug in the shaft 17 of the gearbox housing. On the drive shaft 18, the toothed cylindrical wheels 19 and 20 are seated on needle bearing bearings. The wheel 19 is permanently engaged with the toothed cylindrical wheel 12, thus forming a larger gear shaft.

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the country house, and the gear spur wheel 20, with the wheel 11, form a low gear. Between the wheels on the drive shaft in the splines, a speed change clutch 21 is installed with a synchronizer with the possibility of movement in the axial direction along the splines. On the spur gears 19 and 20 for engagement with the speed change clutch 21 there are internal teeth. Between screw

8 and speed clutch

with the synchronizer, there is a kinematic connection in the form of a two-arm lever 22 (FIG. 2) installed in the crankcase 2 of the gearbox on the brackets 23. With one arm, the lever 22 enters the slot of the coupling 21, and the other into the groove made on the toothed cylindrical wheel 12. Two extension springs 25 are fastened to the protrusions 24 of the two shoulders. Other spring springs are fixed on the protrusions 26 made in the crankcase 2 of the gearbox.

The jack works as follows.

The drive shaft 18 rotates, transmits the rotation through the speed change clutch 21, which is engaged with it by the gear cylindrical wheel 19, to the gear wheel 12. The gear wheel 12 in turn rotates the screw 8. The gear wheel 20 rotates by a gear wheel 11 and, not being in engagement with the speed change clutch 21, is freely rotated relative to the drive shaft 18. The screw

8, rotating, moves the nut 5, thereby pushing the rod 3. When a load occurs on the screw 8 (for example, when the ball bearing 4 has a support surface), the spring 15 is retracted

into the recess of the crankcase 2 of the gearbox until the gap between the free ring of the bearing 9 and the collar of the crankcase 2 of the gearbox, i.e. as long as the bearing ring does not lie on the crankcase of the gearbox. At the same time, the spring 14 presses another free bearing ring.

9. Clearance between the free ring

and the crankcase determines the amount of movement of the screw in the axial direction.

When moving in the axial direction, the cylindrical gear wheel31

Claims (1)

From 12, mounted on screw 8, the end of its groove rotates the double-arm lever 22 relative to the axis (Fig. 3), which, turning, removes the speed change clutch 21 from engagement, while the springs 25 are expanding. The screw stroke is designed in such a way that the end of the groove on the toothed cylindrical wheel 12 translates the double-arm lever 22 through a plane perpendicular to the axis of the screw. The springs 25 at the same time go into a dead position and, compressing the cone surfaces of the synchronizer and the gear wheel 20, tighten. When the speeds of the drive shaft 18 and the gear wheel 20 are equalized, the springs introduce the speed change clutch into gear with the gear wheel 20 and press two shoulders. - chag 22 to the opposite end of the groove of the gear wheel 12. The rotation on the screw is transmitted through the gear wheels 20 and 11. When the load on the screw disappears, the spring 15 returns the screw to its initial position. The groove end of the gear 12 rotates the double-arm lever 22, which, moving along the splines of the clutch, turns off the lower gear. Next, the springs, crossing the dead position, include overdrive and push the double-arm lever to the other end of the groove of the gear 12. The formula of the invention Screw jack, comprising body, screw mounted in box 174 and interacting with a cargo nut mounted on a rod mounted for movement in the housing, a screw drive comprising two pairs of gear cylindrical wheels arranged on two parallel drive and driven shafts, the last of which is kinematically connected with the screw, lichas. By the fact that, in order to improve the operational characteristics by automatically changing the speed of the stem extension during forward and reverse travel depending on the magnitude of the load acting on it, the screw is mounted in the housing with axial movement and spring-loaded relative to the housing. mounted on the drive shaft with the possibility of reciprocating movement of the alternating circuit through it of the drive shaft with one of the gears, and the coupling drive including a double-arm lever pivotally connected by the middle part with the body and interacting with one arm with the coupling and the other with the screw, and a spring connected at one end with the one arm of the lever and the other at the point on the plane passing through the axis of rotation of the lever and the point of attachment of the spring on the lever with the latter in the middle position. 2fy .25  23 Have / 7 //////// /////////////////// Z. 26 Fiz. 2 Thebes. 3