JP2003041502A - Method of packing resin into variable pad and resin packer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To (a) reduce the curing time of resin; (b) enhance the reliability of operation; (c) facilitate the post-processing of the remaining resin; (d) enable use of a pad without a one-way valve; and (e) eliminate the need for an operator to pressurize each pad until the resin cures. SOLUTION: This method includes a) preparing an airtight bag 72 containing a main agent of a packed resin in an amount slightly greater than the amount of resin packed in one variable pad 38; b) preparing a container containing a curing agent in an amount sufficient to cure the main agent in the bag; c) adding the curing agent prepared in the process b) to the bag, then mixing the components together, and connecting the bag to the unpacked variable pad by means of a tube 88; d) loading the bag into a pressure storage type resin packer 70; e) using the resin packer to force-feed the uncured packed resin in the bag into the variable pad under roughly constant pressure; f) waiting for the packed resin to cure under the condition produced in the process e); and g) taking out the bag from the resin packer once the resin has cured, and using the resin packer repeatedly for other variable pads.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for filling resin into a resin-injection-type variable pad interposed between a rail bottom surface and a tie plate together with a track pad, and a resin filler used in this method. It is a thing.

[0002]

2. Description of the Related Art When fastening a rail to a track slab or a PC sleeper, a tie plate is fixed to these track slabs and a PC sleeper, and a rail is held by holding a variable pad and a track pad on this tie plate. ing.

The variable pad is a bag in which resin is injected, and the height of the rail surface is adjusted by adjusting the injection amount of resin. The resin is cured after being poured into the bag.

The track pad is placed on the variable pad, and a rubber plate is bonded to the lower surface of a metal plate such as a stainless plate. This rubber absorbs the impact of the rail. The metal plate makes the rail slippery when the rail abutting on the upper surface thereof expands or contracts or moves due to temperature change or the like.

Heretofore, the following two methods have been conventionally used as a method of filling the variable pad with resin. The first method uses a dedicated pump. FIG. 5 is a sectional view showing an example of this pump.

In FIG. 5, reference numeral 100 is a liquid tank (tank), which has a cylindrical shape with an open top. The lid 102 can be airtightly attached to this liquid tank by a tightening mechanism (not shown). Into this liquid tank 100, the amount of 10 to 20 variable pads of the filling resin and the curing agent are put and mixed uniformly.

A manual pump 104 is attached to the lid 102. This pump 104 is a pump body 106 that is fixed airtightly on the upper surface of a lid 102 with packing.
And a suction tube 1 that is fixed to the pump body 106 and extends vertically through the lid 102 into the liquid tank 100.
08, and a rod 110 projecting upward from the suction tube 108 through the pump body 106.
And a plunger 11 that is attached to the lower end of the rod 110 and slides in close contact with the inner surface of the suction tube 108.
Have 2 and. A one-way valve 114 that guides the liquid in the liquid tank 100 into the suction tube 108 is attached to the lower end of the suction tube 108.

The plunger 112 is the suction tube 1.
The interior of 08 is divided into a lower chamber 116 and an upper chamber 118, and a one-way valve 120 for guiding the liquid from the lower chamber 116 to the upper chamber 118 is attached to the inside of the plunger 112. The upper chamber 118 of the suction tube 108 is the pump body 1
The discharge port 122 provided at 06.

The upper end of the rod 110 is a push handle 12
Connected to four. The hand push handle 124 has a connecting point 1 between the hand push end side (the right end side in FIG. 5) and the rod 110.
It is supported by the rocking member 128 between 26 and 26. That is, since the upper end of the rod 110 moves up and down only in the vertical direction, when the hand pushing end of the handle 124 is pushed downward, the handle 124 slightly swings the swinging member 128 while connecting the rod 110 at its tip. The point 126 is raised vertically without moving back and forth. Discharge port 122
Is connected to one end of a tube (not shown), and the other end of the tube is connected to a variable pad (not shown).

Therefore, if the handle 124 is manually operated up and down, the rod 11 is lifted by the lifting operation of the handle 124.
0 goes down. Therefore, the lower one-way valve 114 is closed, and the liquid in the lower chamber 116 passes through the upper one-way valve 120 and the upper chamber 118.
Flow into. If you push down the handle 124, the rod 110
Rises. At this time, since the upper one-way valve 120 is closed, the pressure in the upper chamber 118 rises. Therefore, the liquid in the upper chamber 118 is pumped from the discharge port 122 through the tube to the variable pad.

In this case, the variable pad is provided with a one-way valve for preventing backflow of liquid. Therefore, after filling the variable pad with liquid, the pump 104 can be disconnected from the variable pad. Pump 1 after filling one variable pad
04 is connected to another variable pad, and different variable pads are sequentially filled with the liquid. This liquid cures after a predetermined curing time.

The second method conventionally used is shown in FIG. In this method, a mixed solution (a mixed solution of a main resin of a filling resin and a curing agent) for one variable pad is filled in a bag 150 made of a flexible resin (for example, polyethylene) in advance. Then, the bag 150 is sandwiched between the sandwich plates 152 and 154, and pressure is applied by the hands and feet. Here, the sandwich plate 154 is the shaft 1
56 is rotatably connected to the lower sandwich plate 152 by 56,
The sandwich plate 154 is biased in the closing direction by a torsion spring (torsion spring) 158 mounted on the shaft 156. The spring 158 is insufficient to pressurize the liquid in the bag 150, and it is necessary to press the upper sandwiching plate 154 manually.

The lower sandwich plate 152 is formed with an opening 162 for passing the one-way valve 160 attached to the bag 150. The one-way valve 160 projects downward from the opening 162 to the sandwich plate 152. The one-way valve 160 is connected to the variable pad 166 by a tube 164.

[0014]

The first conventional method using the pump 104 shown in FIG. 5 has the following problems. (A) A large amount (1
Since the main component of the filled resin and the curing agent (for 0 to 20 sheets) are mixed and put in, all the resins must be used up before the curing of the resin begins. Therefore, the work has to be done in a hurry, and the certainty of the work becomes low. (B) Since it is necessary to set a long curing time for the resin, it takes a long time to cure the pad and it takes time to complete the work. In addition, the resin may be hardened into a semi-gel state during the work, but since such a material is filled in the pad, the finished product is likely to vary from pad to pad. (C) When the pump is left with the resin left, the resin hardens and the pump becomes unusable. Therefore, after the use, the remaining resin is always discarded, and the amount of wasted resin increases. (D) Since the pump has to cleanly remove the resin after use, it is troublesome to dispose of it. (E) Since it is necessary to use a pad with a one-way valve, the pad itself becomes expensive.

The second method using the bag 150 shown in FIG. 6 has the following problems. (A) Since the sandwiching plate (154) is manually pressed, the pressing force is unstable. Therefore, the one-way valve (160) is attached to the pad (166) side or the bag (150) side and the inside of the pad is kept. It is necessary to prevent the resin pressure from fluctuating. This makes the pad or tube expensive by providing a one-way valve. (B) Since it is necessary to manually push the sandwich plate until the resin hardens, the operator cannot perform another work during that time, and the work efficiency is poor.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a first object thereof is to provide a resin filling method for a variable pad which can solve the problems of the conventional methods.
That is, it is a first object of the present invention to provide a resin filling method for a variable pad that can achieve the following objects. (A) Increase the work efficiency by setting the curing time of the resin short. (B) The work can be performed calmly for each pad, and the reliability of the work is improved. (C) Even if the resin remains, the subsequent treatment can be facilitated. That is, it is unnecessary to wash the pump, and the amount of resin left unused is reduced. (D) A pad without a one-way valve can be used, which makes the pad inexpensive. (E) It is unnecessary for the operator to apply pressure until the resin is cured for each pad. Therefore, the worker can perform other work while waiting for the resin to cure. A second object of the present invention is to provide a resin filler used directly for carrying out this method.

[0017]

According to the present invention, the first object is to interpose a track pad between the tie plate and the bottom of the rail, and the height of the rail on the track pad can be adjusted by the amount of resin injected. In the resin filling method for a variable pad according to the method, a) prepare an airtight bag containing a base resin of a filling resin that is slightly larger than the filling amount of one variable pad; and b) an amount to cure the main component of the bag. C) prepare a container containing the curing agent; c) add the curing agent prepared in step b) to the bag and mix, and connect this bag to the unfilled variable pad with a tube; Loading in a pressure-accumulation type resin filling device; e) pumping the uncured filling resin in the bag to the variable pad at a substantially constant pressure by the resin filling device; f) step e)
Wait for the filling resin to harden in the state of g.) G) When the resin has hardened, take out the bag from the resin filling device and repeatedly use this resin filling device for other variable pads; And a method of filling a variable pad with resin.

According to this method, since it is not necessary to provide a one-way valve in the resin flow path from the pump to the variable pad, a variable pad without a one-way valve can be used. The variable pad has a maximum capacity of about 360 cc, the resin is polyester or the like, and the curing time can be about 15 minutes or less, and the pot life can be about 4 minutes or less. Further, the tube connecting the pump and the variable pad has a sufficiently large inner diameter, for example, if the inner diameter is 8 to 9 mm, the flow resistance of the resin becomes small, and the resin can be pumped sufficiently smoothly by a pressure accumulating pump.

According to the present invention, the second object is a resin filler used in the method according to any one of claims 1 to 4, which is an uncured filler obtained by mixing a main component of a filler resin and a curing agent thereof. A loading chamber for loading an airtight bag containing a resin, a movable wall that serves as a wall of the loading chamber and changes the volume of the loading chamber,
A resin filling device comprising: a pressure accumulating member that presses the movable wall in a direction that reduces the volume of the loading chamber; and a pressure drive unit that pressurizes the pressure accumulating member and holds it in a pressurized state. It

In this case, the pressure accumulating member may be a compression coil spring, and the pressurizing drive unit may be constituted by having a ratchet mechanism which sends a push rod for compressing the coil spring in one direction by manual force.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing an example of a rail slab rail fastening device to which an embodiment of the present invention is applied (direct connection type 8 general use), FIG. 2 is an exploded perspective view of its essential parts, and FIG. FIG. 4 is a diagram of a resin filling device according to the present invention, and FIG.

In FIG. 1, reference numeral 10 is a track slab, and this slab 10 is a PC (Prestressed concrete) plate having a length of several meters in the rail length direction, and is positioned and laid on the roadbed. An embedding plug collar 12 is embedded in advance at a predetermined position in this slab 10.

In the figure, 14 is an iron tie plate having a length of about 18 cm in the rail length direction. The tie plate 14 is positioned and placed on the slab 10 with an insulating plate 16 such as a rubber mat interposed therebetween. The tie plate 14 is fixed to the slab 10 by an anchor T bolt 18 and a nut 20.

The T bolt 18 has a T-shaped bolt head 1 at the lower end.
8a. The embedded plug collar 12 has the bolt head 18
An engaging portion 12a having a flat cross-section that is substantially D-shaped so that the bolt a passes through, and the bolt head 18a is inserted into the bolt head 18a from above and rotated by 90 °. To be engaged with.

The T-bolt 18 and the tie plate 14 are electrically insulated by the insulating collar 22. The insulating collar 22 has a cylindrical boss portion and a flange portion that expands from the upper end of the boss portion 24 in the outer diameter direction. The insulating collar 22 is manufactured, for example, by injection-molding a polycarbonate resin containing about 8% by weight of glass short fibers.

As shown in FIG. 1, an insulating plate 16 and a tie plate 14 are passed through the T-bolt 18, and an iron cover plate 28, an insulating collar 22, a washer 30, a spring washer 32, and a washer 34 are passed through the T-bolt 18. It And finally the nut 20
Is screwed on and tightened. Here, the boss portion of the insulating collar 22 enters into the bolt holes of the cover plate 28 and the tie plate 14. In this way, the tie plate 14 and the T-bolt 18 are electrically insulated by the insulating collar 22.

In FIG. 1, reference numeral 36 denotes a rail, and a resin injection type variable pad 38 and a track pad 40 for adjusting the rail height.
It is put on the tie plate 14 via. The leaf spring 42 that presses the rail 36 includes a bolt 44 and a nut 4.
It is clamped and fixed to the tie plate 14 by 6.

The tie plate 14 is integrally formed with protruding walls 48, 48 for guiding the rail bottom portion. These protruding walls 48, 48 stand up with a space substantially corresponding to the width of the bottom portion 36A of the rail 36. The variable pad 38 and the track pad 40 are laid between the projecting walls 48, 48, and the bottom portion 36A of the rail 36 is placed thereon. The rail 36 is restricted from moving in the left-right direction (width direction) by the protruding walls 48, 48.

Notch portions 50, 50 are formed on the projecting walls 48, 48 so as to extend downward, so as to cross the width direction.
A substantially trapezoidal bolt head (not shown) of the bolt 44 engages here.

The track pad 40 has a metal plate 52 made of a stainless steel plate and a rubber plate 54 adhered to the lower surface of the metal plate 52. The metal plate 52 is the tie plate 14
Is made longer than the length of the rail in the longitudinal direction, and both end portions sandwiching a portion corresponding to the length of the tie plate 14 project in the width direction to form a tongue portion 56. The four tongue-shaped portions 56 are bent downward at the tips thereof. These tongues 56 engage with the projection walls 48 of the tie plate 14 to position them.

Next, the variable pad 38 will be described. The variable pad 38 is formed by injecting a resin into a resin bag and curing the resin. This bag has a flat shape as shown in FIG. 2, and a pair of upper and lower sheets having a predetermined shape is cut out from polyethylene or a laminated sheet of polyethylene and nylon, and the peripheral edges of these upper and lower sheets are welded to form a bag shape. It was done.

The variable pad 38 is, as shown in FIG.
A resin injection port 58 and an air vent port 60 are formed at diagonal positions of the projecting portions at both ends, which are longer than the dimension of filling the space between the projecting walls 48 of the tie plate 14 in the rail longitudinal direction. The inlet 58 and the air vent 60 each extend diagonally.

At other diagonal positions of the variable pad 38, projecting portions 62, 62 are provided so as to project in the width direction. Therefore, when the variable pad 38 is set on the tie plate 14, the inlets 58, the air vents 60, and the protrusions 62, 6 at the four corners are set.
2 engage the edges of the protruding walls 48, 48, respectively, so that the variable pad 38 is properly aligned with the tie plate 14.

The above-mentioned track pad 40 is superposed on the variable pad 38. At this time, the track pad 40 has both end portions protruding to both sides of the tie plate 14, and the tongue portion 56
Is both end surfaces of the tie plate 14, that is, the protruding walls 48, 48
Engage with both end faces of the (see FIG. 1). In this way, the four tongue portions 56 engage with both end surfaces of the projecting walls 48, 48, respectively, so that the track pad 40 is accurately positioned. That is, the tongue portion 56 functions as a stopper that restricts the movement of the track pad 40.

The height of the rail 36 is adjusted with the rail 36 placed on the track pad 40. This operation is performed by injecting resin from the injection port 58 with the air vent port 60 of the variable pad 38 opened, and closing the air vent port 60 with the air released to control the injection amount. This resin injection is performed by the pressure accumulated in the resin filler 70, which will be described later, and by applying a predetermined pressure to the resin to continue, the rail height is made appropriate and the resin is cured after a predetermined time. After that, the injection port 60 may be closed, but the injection port 60 may not be closed after the resin is sufficiently cured.

Next, the resin filler 70 will be described with reference to FIGS. The resin filling device 70 pressurizes a resin bag 72 containing a filling resin main agent and a curing agent via a pressure accumulating member such as a compression coil spring 74. Bag 72 here
Is an airtight one made of a polyethylene sheet or a laminated sheet of polyethylene and nylon. In this bag 72, an amount (about 360 cc) of a filling resin main agent (for example, polyester) sufficient to fill one variable pad 38 is put in advance and stored. Immediately before construction, a predetermined amount (about 20 cc) of a dedicated curing agent is mixed into this bag 72, mixed well, and loaded into the resin filling device 70.

As shown in FIG. 3, the resin filling device 70 has a vertically long substantially rectangular tube-shaped case 76, a horizontal partition wall 78 fixed in the case 76, and faces the partition wall 78 above. Movable wall 80 movable up and down, the compression coil spring 74 as a pressure accumulating member that presses the movable wall 80 from above, and a pressure drive that pressurizes the coil spring 74 from above and holds it in a pressurized state. And a section 82.

A loading chamber 84 surrounded by the inner wall of the case 76 is formed between the partition wall 78 and the movable wall 80. Here, a part of the front surface of the case 76 serves as a door 86 that opens and closes the loading chamber 84, and the door 86 can be locked at the closed position. Although only the main component is put in the bag 72 in advance, the hardener contained therein is injected from a small container containing a predetermined amount (about 20 cc) of the hardener just before construction. Then, after thoroughly mixing with the main agent, the bag 72 is loaded into the loading chamber 84, and the door 86 is closed and locked.

Here, one end of a tube 88 is connected to the cap 72A of the bag 72. The other end of the tube 88 is connected to the injection port 58 of the variable pad 38.
The bag 72 is set in the loading chamber 84 so that the cap 72A and the tube 88 project downward from the notch 78A provided in the partition wall 78.

The pressurizing drive section 82 is a push rod 90 which projects upward from the case 76 and can move up and down, and a circular disk 92 which is fixed to the lower end of the push rod 90 and presses the upper end of the coil spring 74 downward. A manual ratchet mechanism 94 provided on the upper surface of the case 76 for feeding the push rod 90 downward, and a stopper 96 for the push rod 90.
Have and.

The ratchet mechanism 94 is a fixed handle 94.
By gripping A and the movable handle 94B, a claw provided at the tip of the movable handle 94B engages with the push rod 90 to feed the push rod 90 downward by a small amount. The stopper 96 is a long plate 96A having the push rod 90 inserted through a hole having a diameter slightly larger than that of the push rod 90, and an engagement piece provided on the fixed handle 94A so that the tip of the long plate 96A is engaged. 96B and long plate 96
A coil spring 96C that gives the upward elasticity habit of A
Have and.

Therefore, in the stationary state, the long plate 96A is pushed upward by the coil spring 96C, and the long plate 96A is tilted, so that the two opposite holes of the push rod 90 are engaged with the push rod 90, and the push rod 90 is pushed. Is restricted from moving upwards.

Fixed handle 94A and movable handle 94B
When the claws of the movable handle 94B push down the push rod 90 by a small amount by grasping and, the stopper 96
The long plate 96A slightly pushes the coil spring 96C and swings downward. At this time, the positions where the inner edges of the two holes of the elongated plate 96A facing each other engage with the push rod 90 are changed, and the push rod 90 is prevented from returning upward again.

When the push rod 90 is lowered by the reciprocating movement of the movable handle 94B in this manner, the disk 92 at the lower end thereof compresses the coil spring 74. As a result, the lower end of the coil spring 74 compresses the bag 72 via the movable wall 80. From the compressed bag 72, the liquid therein (mixed liquid of the main agent and the curing agent) is pressure-fed to the variable pad 38 via the tube 88.

By compressing the coil spring 74 by operating the movable handle 94B, the pressure applied to the bag 72 can be maintained. That is, if the coil spring 74 is compressed as shown in FIG.
The liquid pressure continues to be applied to 8 and the liquid continues to flow to the variable pad 38. Since the liquid starts to flow out from the air vent hole 60, the air vent port 60 is closed. Then, if the stored pressure is added by leaving it as it is, or by operating the movable handle 94B at a proper time to further compress the coil spring 74, the liquid will harden soon and the state of FIG.

Variable pad 38 after the resin is completely cured
It suffices to cut the injection port 58 of. When it is not possible to wait for sufficient curing, the injection port 58 may be closed with a fastener. When the filling of one variable pad 38 is completed in this way, the long plate 96A of the stopper 96 is slightly pushed down by the fingertip to release the meshing between the hole of the long plate 96A and the push rod 90, and the push rod 9
Increase 0. Then, the bag 72 is taken out from the resin filling device 70, another bag 72 for the variable pad 38 is loaded, and the resin is filled in the same manner.

Although the compression coil spring 74 is used as the pressure accumulating member in this embodiment, rubber elasticity or pneumatic elasticity may be used instead. If the inner diameter of the tube 88 that connects the resin filling device 70 and the variable pad 38 is small, the flow resistance of the liquid may increase and the internal pressure of the variable pad 38 may not be sufficiently increased. Therefore, it is preferable to make the inner diameter of the tube 88 larger than the conventional one, for example, 8 to 9 mm.

The pressurizing drive unit may be manually driven, but may be a foot-operated type, or power other than human power, for example, power of an electric motor, air pressure for power, or the like may be used.

[0049]

According to the inventions of claims 1 to 4, the following effects can be obtained. (A) Since only one variable pad of resin can be put in the bag, the amount of resin wasted is reduced. (B) Since the force accumulated in advance is used while pressurizing the resin and waiting for its curing, it is not necessary for the operator to constantly pressurize and be present, and during that time, another work such as work on another variable pad can be performed. You can do it. (C) Since the resin is continuously pressurized at a constant pressure, the one-way valve is unnecessary in the resin flow path. Therefore, a valveless pad can be used, which makes the pad inexpensive. (D) Since the curing time of the resin can be set short, the work efficiency is improved. (E) Since the bag is only pressurized and the liquid pump is not used, it is not necessary to wash the pump or the like after the resin is hardened, and the work efficiency is improved. According to the inventions of claims 5 and 6, a resin filling device directly used for carrying out this method can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a track fastening device showing an application example of an embodiment of the present invention.

FIG. 2 is an exploded perspective view of a main part

FIG. 3 is a diagram showing a resin filler.

FIG. 4 is an operation explanatory view of a resin filling device.

FIG. 5 is a diagram showing a pump used in a conventional method.

FIG. 6 is an explanatory diagram of another conventional method.

[Explanation of symbols]

14 tie plate 36 rails 36A rail bottom 38 variable pad 40 track pad 70 Resin Filler 72 bags 74 Compression coil spring (pressure accumulating member) 80 movable walls 82 Pressure drive unit 84 loading chamber 88 tubes 90 push rod 94 ratchet mechanism 96 stopper

Continued front page    (72) Inventor Fumio Yamamoto             6-1073 God, Minamitsukaguchi-cho, Amagasaki-shi, Hyogo             Inside the East Paint Co., Ltd. (72) Inventor Yoshitaka Murata             6-1073 God, Minamitsukaguchi-cho, Amagasaki-shi, Hyogo             Inside the East Paint Co., Ltd. F-term (reference) 2D056 AD03

Claims (6)

[Claims] 1. A resin filling method for a variable pad, which is interposed between a tie plate and a rail bottom surface together with a track pad, and which makes it possible to adjust the height of the rail on the track pad by adjusting the amount of resin injected. Prepare an airtight bag containing a base resin of a filling resin that is slightly larger than the filling amount of one variable pad; b) Prepare a container containing a curing agent in an amount that cures the main component of the bag; c ) Add the curing agent prepared in step b) to the bag and mix, and connect this bag to the unfilled variable pad with a tube; d) load the bag into a pressure accumulating resin filler; e) The uncured filling resin in the bag is pressure-fed to the variable pad by the resin filling device at a substantially constant pressure; f) Waiting for the filling resin to harden in the state of step e); g) The resin filling device when the resin hardens. Remove the bag from this resin filling machine Resin filling method for a variable pad and having each of the steps described above; repeatedly used for other variable pad. 2. The resin filling method for a variable pad according to claim 1, wherein there is no one-way valve in the flow path of the uncured filled resin from the bag to the variable pad. 3. The variable pad has a maximum capacity of about 360 cc, the resin is polyester, and the resin curing time is about 15
The method of filling a variable pad resin according to claim 1 or 2, wherein the time is within a minute, and the pot life is about 4 minutes. 4. The resin filling method for a variable pad according to claim 1, wherein the tube used in step c) has an inner diameter of 8 to 9 mm. 5. A resin filler used in the method according to any one of claims 1 to 4, wherein an airtight bag containing an uncured filler resin in which a main component of the filler resin and a curing agent thereof are mixed is loaded. Loading chamber, a movable wall that serves as a wall of the loading chamber and that changes the volume of the loading chamber, a pressure accumulating member that presses the movable wall in a direction that reduces the volume of the loading chamber, and a pressurizing state by pressurizing the pressure accumulating member. And a pressure drive unit for holding the resin filling unit. 6. The resin filler according to claim 5, wherein the pressure accumulating member is a compression coil spring, and the pressurizing drive unit has a ratchet mechanism that sends a push rod for compressing the compression coil spring in one direction by manual force.