GB2188884A

GB2188884A - Resilient pivoting cab arrangement

Info

Publication number: GB2188884A
Application number: GB08705735A
Authority: GB
Inventors: John Arthur Needham Bennett; David Ian Ford
Original assignee: ERF Ltd
Current assignee: ERF Ltd
Priority date: 1986-03-14
Filing date: 1987-03-11
Publication date: 1987-10-14
Also published as: GB8705735D0; GB2188884B; GB8606398D0

Abstract

An improved suspension arrangement for the cab of commercial vehicles comprises a cross member 10 on which is fixed an arm 14 supporting an arrangement 16 which pivotally attaches a first mounting member 18 to the arm. A pair of resilient rubber bushes 22 are provided in the arrangement 16 to resist pivotal movement of the member 18 about the arm. The member 18 pivotally mounts the cab about a pivot pin 12. A rubber compression spring 30 including a bump stop 34, is attached between the underside of the member 18 and an upper surface of the arm. A shock absorber 38 is fixed between the outer end of the member 18 and the cross member 10. <IMAGE>

Description

SPECIFICATION Improvements in or relating to suspension arrangements The present invention concerns an improved suspension arrangement, especially but not exclusively an improved suspension arrangementforthe cab of a commercial vehicle.

Most modern commercial vehicles have a cab which is constructed as a unit and pivotally mounted about one edge, normally the front edge, to the vehicle chassis so that the cab can be tilted forward to expose the vehicle engine, transmission, etc. for maintenance and repair purposes.

Most cabs of this type are mounted by a resilient suspension with a view to separating the cab from sudden chassis movement and vibration. In the past certain suspensions have given a "soft" feel which has not been conducive to driver comfort. On the other hand, certain other suspensions have given a "hard" feel andwhilethis gives rise to increased driver acceptance, it has not served in efficiently reducing the transmission of vibration and noise.

It is an object of the present invention to obviate or mitigate these disadvantages to obviate or mitigate these disadvantages.

According to the present invention there is provided a suspension arrangement comprising first membertowhich a unitto be suspended ispivotally mqunted and a second member adapted forfixing to a support structure, the first and second members being connected buy a pivotal mounting which includes a torsional damping arrangement, and a resilient supportmemberforsupportingthefirstmemberon the second member.

Preferably the torsional damping means in the pivotal mounting includes a resilient bush of natural or synthetic rubber surrounding and fixed at its inner surface to a pivot pin fixed to one of said members and fixed at its outer surface to the other of said members.

Preferably the support means comprises a natural or synthetic rubber member sandwiched between the first and second members. The member may be so designed as to give a progressive rate spring force.

Preferably said support means includes movement limiting means fixed to one member and adapted to abut the other member when a predetermined movement between the members has been exceeded.

Preferably also the suspension arrangement includes a shock absorber connected directly or indirectly between thefirstand second members ata point thereon spaced from said pivotal mounting.

An embodiment ofthe present invention will now be described byway of example only with reference to the accompanying drawings, in which:- Figure 1 shows an elevation of a suspension arrangement; and Figure 2 shows a partial sectional plan.

Figure 1 shows the front cross-member 10 of the chassis of a heavy commercial vehicle to which a cab unit has to be pivotally mounted about a pivot pin 12.

A rearwardly directed arm 14 is fixed to the upper surface of the cross-member 10 and supports a pivot arrangement 16 by which a first mounting member 18 is pivotally attached to the arm or second member 14.

A pivot pin 20 ofthe pivot arrangement 16 is mounted against rotation on the first memberor arm 14 and has fixed thereto a pair of resilient bushes 22 of natural or synthetic rubber which in turn are fixed by their outside surfaces to the interior of the circular through passage 24 extending through the frist member 18. It will be realised therefore thatthefirst member 18 can pivotaboutthearm 14 butthatthis pivotal movement is resisted by the resilience ofthe bushes 22 attached between the first and second members.

To control the downward movement ofthefirst member relative to the second member and to provide a reaction against the downward load exerted by the cab through the pivot pin 12 there is provided a support arrangement which includes a natural or synthetic rubber compression spring 30 which is attached bya bolt 31 to the underside ofthefirst member 18 and which has a blind downwardlyopen- ing passage 32 therein, the passage 32 accommodating a bump stop 34 which serves also as the nut for the fixing bolt 31. A polyurethane pad 36 is fixed to an uppersurfaceofthe arm 14 in the path of down- ward movement of the bump stop 34 but normally spaced from it. The spring 30 is a progressive rate spring.The support arrangement is completed by an hydraulic or pneumatic shock absorber or damper 38 fixed between the across member 10 and the outer end ofthefirstmemberl8.

Various modifications can be mde without departing from the scope of the invention. For example, alternative portional damping means can be provided for the pivot arrangement 16. In a further modification the second member 14 may be formed integrally with the cross member 10. Alternative support arrangements may be employed, for example by appropriate amendment ofthe mounting means, the compression member can be substituted by a tension member. Additonallythe shock absorber may be dispensed with or may be located at a different position.

It has been found, however, that the suspension gives a good "feel" to the driver of the cab while still providing sufficient noise and vibration absorption if the torque member of the pivot arrangement and the compression member of the support arrangement are fabricated from natural or synthetic rubber.

1. A suspension arrangement comprising a first member to which a unit to be suspended is pivotally mounted and a second member adapted forfixing to a support structure, the first and second members being connected by a pivotal mounting which includes a torsional damping arrangement, and a resilient support member for supporting the first member on the second member.

2. An arrangement as claimed in claim 1, in which the torsional damping means in the pivotal

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in or relating to suspension arrangements The present invention concerns an improved suspension arrangement, especially but not exclusively an improved suspension arrangementforthe cab of a commercial vehicle. Most modern commercial vehicles have a cab which is constructed as a unit and pivotally mounted about one edge, normally the front edge, to the vehicle chassis so that the cab can be tilted forward to expose the vehicle engine, transmission, etc. for maintenance and repair purposes. Most cabs of this type are mounted by a resilient suspension with a view to separating the cab from sudden chassis movement and vibration. In the past certain suspensions have given a "soft" feel which has not been conducive to driver comfort. On the other hand, certain other suspensions have given a "hard" feel andwhilethis gives rise to increased driver acceptance, it has not served in efficiently reducing the transmission of vibration and noise. It is an object of the present invention to obviate or mitigate these disadvantages to obviate or mitigate these disadvantages. According to the present invention there is provided a suspension arrangement comprising first membertowhich a unitto be suspended ispivotally mqunted and a second member adapted forfixing to a support structure, the first and second members being connected buy a pivotal mounting which includes a torsional damping arrangement, and a resilient supportmemberforsupportingthefirstmemberon the second member. Preferably the torsional damping means in the pivotal mounting includes a resilient bush of natural or synthetic rubber surrounding and fixed at its inner surface to a pivot pin fixed to one of said members and fixed at its outer surface to the other of said members. Preferably the support means comprises a natural or synthetic rubber member sandwiched between the first and second members. The member may be so designed as to give a progressive rate spring force. Preferably said support means includes movement limiting means fixed to one member and adapted to abut the other member when a predetermined movement between the members has been exceeded. Preferably also the suspension arrangement includes a shock absorber connected directly or indirectly between thefirstand second members ata point thereon spaced from said pivotal mounting. An embodiment ofthe present invention will now be described byway of example only with reference to the accompanying drawings, in which:- Figure 1 shows an elevation of a suspension arrangement; and Figure 2 shows a partial sectional plan. Figure 1 shows the front cross-member 10 of the chassis of a heavy commercial vehicle to which a cab unit has to be pivotally mounted about a pivot pin 12. A rearwardly directed arm 14 is fixed to the upper surface of the cross-member 10 and supports a pivot arrangement 16 by which a first mounting member 18 is pivotally attached to the arm or second member 14. A pivot pin 20 ofthe pivot arrangement 16 is mounted against rotation on the first memberor arm 14 and has fixed thereto a pair of resilient bushes 22 of natural or synthetic rubber which in turn are fixed by their outside surfaces to the interior of the circular through passage 24 extending through the frist member 18. It will be realised therefore thatthefirst member 18 can pivotaboutthearm 14 butthatthis pivotal movement is resisted by the resilience ofthe bushes 22 attached between the first and second members. To control the downward movement ofthefirst member relative to the second member and to provide a reaction against the downward load exerted by the cab through the pivot pin 12 there is provided a support arrangement which includes a natural or synthetic rubber compression spring 30 which is attached bya bolt 31 to the underside ofthefirst member 18 and which has a blind downwardlyopen- ing passage 32 therein, the passage 32 accommodating a bump stop 34 which serves also as the nut for the fixing bolt 31. A polyurethane pad 36 is fixed to an uppersurfaceofthe arm 14 in the path of down- ward movement of the bump stop 34 but normally spaced from it. The spring 30 is a progressive rate spring.The support arrangement is completed by an hydraulic or pneumatic shock absorber or damper 38 fixed between the across member 10 and the outer end ofthefirstmemberl8. Various modifications can be mde without departing from the scope of the invention. For example, alternative portional damping means can be provided for the pivot arrangement 16. In a further modification the second member 14 may be formed integrally with the cross member 10. Alternative support arrangements may be employed, for example by appropriate amendment ofthe mounting means, the compression member can be substituted by a tension member. Additonallythe shock absorber may be dispensed with or may be located at a different position. It has been found, however, that the suspension gives a good "feel" to the driver of the cab while still providing sufficient noise and vibration absorption if the torque member of the pivot arrangement and the compression member of the support arrangement are fabricated from natural or synthetic rubber. CLAIMS

2. An arrangement as claimed in claim 1, in which the torsional damping means in the pivotal mounting includes a resilient bush of natural orsynthetic rubber surrounding and fixed at its inner surface to a pivot pin fixed to one of said members and fixed at its outer surface to the other of said members.

3. An arrangement as claimed in claims 1 or2, in which the support means comprises a natural or synthetic rubber member sandwiched between the first and second members.

4. An arrangement as claimed in claim 3, in which the rubber member is designed so as to give aa progressive rate spring force.

5. An arrangement as claimed in any ofthe preceding claims, in which the support means includes movement limiting means fixed to one member and adapted to abut the other memberwhen a predetermined movement between the members has been exceeded.

6. An arrangement as claimed in any ofthe preceding claims, including a shock absorber connected directly or indirectly between the first and second members at points thereon spaced from said pivotal mounting.

7. An arrangement as claimed in any of claims 1 to 5, including a damper connected directly or indirectly between the first and second members at points thereon spaced from said pivotal mounting.

8. Asuspension arrangement substantially as hereinbefore described with reference to the accompanying drawings.

9. Any novel subject matter or combination including novel subject matter herein disclosed, whether or not within the scope of or relating to the same invention as any ofthe preceding claims.