GB2075630A - Rod assembly for a hydraulic shock absorber - Google Patents
Rod assembly for a hydraulic shock absorber Download PDFInfo
- Publication number
- GB2075630A GB2075630A GB8041608A GB8041608A GB2075630A GB 2075630 A GB2075630 A GB 2075630A GB 8041608 A GB8041608 A GB 8041608A GB 8041608 A GB8041608 A GB 8041608A GB 2075630 A GB2075630 A GB 2075630A
- Authority
- GB
- United Kingdom
- Prior art keywords
- piston rod
- lock nut
- fixture
- assembly
- shock absorber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60G—VEHICLE SUSPENSION ARRANGEMENTS
- B60G13/00—Resilient suspensions characterised by arrangement, location or type of vibration dampers
- B60G13/001—Arrangements for attachment of dampers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60G—VEHICLE SUSPENSION ARRANGEMENTS
- B60G15/00—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type
- B60G15/02—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type having mechanical spring
- B60G15/06—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type having mechanical spring and fluid damper
- B60G15/067—Resilient suspensions characterised by arrangement, location or type of combined spring and vibration damper, e.g. telescopic type having mechanical spring and fluid damper characterised by the mounting on the vehicle body or chassis of the spring and damper unit
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/32—Details
- F16F9/54—Arrangements for attachment
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Fluid-Damping Devices (AREA)
- Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)
- Pistons, Piston Rings, And Cylinders (AREA)
Abstract
A hydraulic shock absorber assembly comprises a piston rod 3 connected at one end to a piston working in a cylinder 2 and at the other end to a fixture 4 for connection to a vehicle axle. The fixture 4 is screwed on to an external thread on the end of the piston rod 3 and is held by a lock nut 7 having an unthreaded cylindrical portion 11 extending over an unthreaded portion of the piston rod and press- fitted thereto so as to transfer the maximum bending moment to a point on the unthreaded portion of the piston rod 3, thus greatly improving the durability of the assembly. <IMAGE>
Description
SPECIFICATION
Rod assembly for a hydraulic shock absorber
This invention relates to an assembly comprising a piston rod for a hydraulic shock absorber, a fixture for connection to a vehicle axle and which is screwed on to an external thread on the end of the piston rod and a lock nut.
For economy of energy and fuel, there has been a recent tendency to reduce the body weight of motor bicycles and automobiles. In this connection, it is especially desirable to reduce the weight of the shock absorbers used to suspend the body of such vehicles.
Therefore, it is desirable to make the piston rods as thin as practicable. However, since not only axial forces but also transverse forces due to vibrations of the vehicle body are applied to the hydraulic shock absorbers the piston rods are liable to be bent or broken if the rods are made excessively thin, the failure occurring at the base of the fixture screwed onto the end of the piston rod. Therefore the piston rods of hydraulic shock absorbers need to meet the contradictory requirement for reduction in weight without loss of strength.
In an assembly according to the invention and comprising a piston rod, fixture and lock nut as set out above, the lock nut has an unthreaded cylindrical portion extending over an unthreaded portion of the piston rod and press-fitted thereto and the fixture is screwed onto the external thread on the piston rod on the opposite side of the lock nut to the unthreaded cylindrical portion.
As a result, the maximum bending moment applied to the piston rod, which occurs at the end of the lock nut, acts on an unthreaded part of the piston rod which is thus much better able to resist the stress than the corresponding threaded part in prior art constructions, as will be understood more fully by reference to the accompanying drawings, which illustrate an example of assembly in accordance with the invention and the results of comparative tests applied to it in which: Figure 1 is an elevation of the assembly fitted to a hydraulic shock absorber;
Figure 2 is an enlarged longitudinal section showing an essential portion of the assembly of Fig. 1;
Figure 3 is also an enlarged longitudinal section showing the same portion as in Fig. 2 while it is being assembled; and
Figure 4 is a graphical presentation illustrating the durability of an assembly according to the present invention in comparison with that of an assembly according to the prior art.
With reference to Fig. 1, a piston slidably fitted in the cylinder 2 of a hydraulic shock absorber 1 is connected to a piston rod 3 for transmission of the shock absorbing force. A fixture for connecting the shock absorber to the axle of a vehicle is screwed on the lower end portion of the piston rod 3 through a spring seat 6, which is disposed to receive one end of a coil spring 5, and is fixed by means of a lock nut 7. The other end 5b of the coil spring 5 is seated upon a spring seat 8 which is attached to the outer circumference of the cylinder 2. A fixture 9 for connecting the other end of the shock absorber to the vehicle body is disposed at the upper end of the cylinder 2.
The fixing assembly for the fixture 4 at the lower end is shown in Fig. 2 to an enlarged scale. The end portion of the piston rod 3 is formed with an external thread 10 on to which the lock nut is first screwed. Then, after the spring seat 6 has been fitted, the fixture 4 is screwed on to the thread 1 0. The lock nut 7 is formed with a cylindrical portion 11 which is press-fitted on the thread less portion of the piston rod 3 and initially has a greater internal diameter than the diameter of the piston rod 3 so that it clears the threaded portion when the lock nut 7 is screwed on to the piston rod 3, as shown in Fig. 3.When in this position, the lock nut 7 has one end held against a jig 1 2 while the cylindrical portion 11 has its leading end 11 a and its outer circumferential portion 11 b press-fitted on to the rod 3 by means of a rotary split-die 1 3.
The inner circumference 1 4 of the die 1 3 includes a gentle taper 1 4b, followed by a steeper taper 1 4 and rotation of the die causes the leading end 11 a of the lock nut 7 to be press-fitted to the rod 3 and the outer circumferentiai portion 11 b to conform with the gentle taper 1 4b while closing the gap between the inner circumference 1 C of the cylindrical portion 11 and the outer circumference of the piston rod 3. After the lock nut 7 has been fitted, the fixture 4 is screwed on to the end portion of the piston rod 3 so that the spring seat 6 is forced against the end face of the lock nut 7.In the case of a hydraulic shock absorber having its coil spring 5 mounted in the cylinder 2, the fixture 4 is forced into direct contact with the end face of the lock nut 7.
In order to determine the effect of the relationship between the size of the gap between the outer circumference of the piston rod 3 and the inner circumference of the cylindrical portion and durability, fatigue tests were carried out using a hollow piston rod having an external diameter of 14 mm and an internal diameter of 4.5 mm such that a stress of 30 kg/mm2 might be established. For the purposes of the tests, the fixture 4 was held in a jig and a transverse force was applied to the piston rod until the stress measured at the point P shown in Fig. 2 reached a value of 30 kg/mm2. This bending moment was applied repeatedly until the piston rod faiied and the number of test cycles prior to failure are given in Table 1 for different sizes of gap. The results of the fatigue tests are tabulated in
Table 1.
Gap (y) Durability in cycles 60 2.2x104 50 3.6x104 40 5.3x104 30 6.9x104 20 8.go104 10 11.4X 104 0 100 x104
The bending moment applied to the piston rod 3 reaches its maximum at a point shown as P in Fig. 2 level with the leading end 11 a and in a construction according to the invention, the portion at the point P is not formed with any thread thereby increasing the resistance to bending or breaking. By constrast, in a fixture according to the prior art which is not formed with the cylindrical portion 11, the maximum bending moment is exerted upon the threaded portion and concentration of stress takes place at the root of the thread leading to a high risk of the piston rod being bent or broken.The results of the fatigue tests on the bending of the rod, in which the durability of an assembly A according to the present invention was compared with that of an assembly B according to the prior art when a bending moment was repeatedly applied to the fixture, are illustrated in Fig. 4.
The piston rod used in Fig. 4 was a hollow rod having an external diameter of 14 mm and internal diameter of 4.5 mm (i.e. the same as for the tests referred to in Table 1), and the gap between the outer circumference of the piston rod and the inner circumference of the cylindrical portion was reduced to zero for the assembly A.
As can be understood from Fig. 4, the durability of an assembly according to the present invention can be improved to at least several tens of times higher than that of an assembly according to the prior art. A point X appearing in Fig. 4 indicates the durability (only for a stress of 30 gk/mm2) of a conventional assembly in which a piston rod having an external diameter of 18 mm and an internal diameter of 4.5 mm and having a modulus of section twice as high as that of the aforementioned rod was used. It can be seen that the durability of a conventional assembly is remarkably inferior to that of an assembly according to the present invention even if the modulus of section of the conventional assembly is doubled.
Claims (4)
1. An assembly comprising a piston rod for a hydraulic shock absorber, a fixture for connection to a vehicle axle and which is screwed onto an external thread on the end of the piston rod and a lock nut, in which assembly the lock nut has an unthreaded cylindrical portion extending over an unthreaded portion of the piston rod and pressfitted thereto, and the fixture is screwed onto the external thread on the piston rod on the opposite side of the lock nut to the unthreaded cylindrical portion.
2. An assembly according to claim 1 in which the piston rod is hollow.
3. An assembly according to claim 1 or claim 2 in which a spring seat is sandwiched between the lock nut and the fixture.
4. An assembly according to any one of the preceding claims wherein the gap between the outer circumference of the piston rod and the cylindrical portion of the lock nut is effectively zero.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1980059940U JPS56162359U (en) | 1980-05-02 | 1980-05-02 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2075630A true GB2075630A (en) | 1981-11-18 |
| GB2075630B GB2075630B (en) | 1983-11-30 |
Family
ID=13127633
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8041608A Expired GB2075630B (en) | 1980-05-02 | 1980-12-31 | Rod assembly for a hydraulic shock absorber |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS56162359U (en) |
| AU (1) | AU525721B2 (en) |
| CA (1) | CA1154041A (en) |
| DE (1) | DE3049562C2 (en) |
| FR (1) | FR2481770A1 (en) |
| GB (1) | GB2075630B (en) |
| IT (1) | IT8147581A1 (en) |
| SE (1) | SE444412B (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4962834A (en) * | 1989-06-14 | 1990-10-16 | Walter K. Napoleon | Threaded removable end mount system for shock absorbers |
| US5044614A (en) * | 1990-02-22 | 1991-09-03 | Rau John A | Shock absorber spring adjuster |
| GB2309282A (en) * | 1996-01-19 | 1997-07-23 | Monroe Auto Equipment Co | Motorcycle front forks |
| EP1526302A1 (en) * | 2003-10-22 | 2005-04-27 | ZF FRIEDRICHSHAFEN Aktiengesellschaft | Damping element |
| EP1722125A1 (en) * | 2005-05-11 | 2006-11-15 | Zf Friedrichshafen Ag | Connecting element for a rod |
| CN104847891A (en) * | 2014-09-11 | 2015-08-19 | 无锡市威特机械有限公司 | Adjusting device for locking cylinder piston rod |
| EP3492361A1 (en) * | 2017-12-01 | 2019-06-05 | Werner Müller | Level adjustment for motorcycles |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1866167A (en) * | 1929-07-22 | 1932-07-05 | William H Lolley | Shock absorber |
| GB562052A (en) * | 1942-12-21 | 1944-06-15 | Automotive Prod Co Ltd | Improvements in or relating to locating and securing devices for use with tubes |
| DE1259213B (en) * | 1962-07-17 | 1968-01-18 | Daimler Benz Ag | Support of a suspension strut consisting of a shock absorber and in particular a coil spring on the frame of a motor vehicle |
| GB1238641A (en) * | 1967-05-01 | 1971-07-07 | ||
| DE1980465U (en) * | 1967-11-15 | 1968-03-07 | Erwin Hausmann | HYDROPNEUMATIC TENSION SPRING. |
| DE2423298C3 (en) * | 1974-05-14 | 1978-11-23 | Volkswagenwerk Ag, 3180 Wolfsburg | Wheel suspension for motor vehicles with a tension strut |
| DE7930294U1 (en) * | 1979-10-23 | 1980-05-29 | Mannesmann Ag, 4000 Duesseldorf | Pipe part for the production of a piston rod for vehicle shock absorbers |
-
1980
- 1980-05-02 JP JP1980059940U patent/JPS56162359U/ja active Pending
- 1980-12-29 SE SE8009159A patent/SE444412B/en not_active IP Right Cessation
- 1980-12-31 DE DE3049562A patent/DE3049562C2/en not_active Expired
- 1980-12-31 GB GB8041608A patent/GB2075630B/en not_active Expired
-
1981
- 1981-01-05 CA CA000367889A patent/CA1154041A/en not_active Expired
- 1981-01-07 AU AU66034/81A patent/AU525721B2/en not_active Expired
- 1981-01-15 IT IT1981A47581A patent/IT8147581A1/en unknown
- 1981-01-20 FR FR8100988A patent/FR2481770A1/en active Granted
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4962834A (en) * | 1989-06-14 | 1990-10-16 | Walter K. Napoleon | Threaded removable end mount system for shock absorbers |
| US5044614A (en) * | 1990-02-22 | 1991-09-03 | Rau John A | Shock absorber spring adjuster |
| GB2309282A (en) * | 1996-01-19 | 1997-07-23 | Monroe Auto Equipment Co | Motorcycle front forks |
| GB2309282B (en) * | 1996-01-19 | 2000-05-10 | Monroe Auto Equipment Co | Modular telescopic front fork assembly |
| EP1526302A1 (en) * | 2003-10-22 | 2005-04-27 | ZF FRIEDRICHSHAFEN Aktiengesellschaft | Damping element |
| EP1722125A1 (en) * | 2005-05-11 | 2006-11-15 | Zf Friedrichshafen Ag | Connecting element for a rod |
| CN104847891A (en) * | 2014-09-11 | 2015-08-19 | 无锡市威特机械有限公司 | Adjusting device for locking cylinder piston rod |
| EP3492361A1 (en) * | 2017-12-01 | 2019-06-05 | Werner Müller | Level adjustment for motorcycles |
Also Published As
| Publication number | Publication date |
|---|---|
| CA1154041A (en) | 1983-09-20 |
| SE8009159L (en) | 1981-11-03 |
| IT8147581A1 (en) | 1982-07-15 |
| FR2481770B1 (en) | 1985-03-29 |
| SE444412B (en) | 1986-04-14 |
| FR2481770A1 (en) | 1981-11-06 |
| JPS56162359U (en) | 1981-12-02 |
| GB2075630B (en) | 1983-11-30 |
| DE3049562A1 (en) | 1981-11-12 |
| IT8147581A0 (en) | 1981-01-15 |
| DE3049562C2 (en) | 1984-12-13 |
| AU6603481A (en) | 1981-11-05 |
| AU525721B2 (en) | 1982-11-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PE20 | Patent expired after termination of 20 years |
Effective date: 20001230 |