GB2564079A - Two tread cassette step unit - Google Patents

Abstract

A foot operated two tread cassette step unit for mounting on a vehicle comprises two treads 8, 9 pivotally mounted to the cassette carrier frame (2, fig 2) with link arms 5, 6 positioned so that when deployed they form a two tread stair and when closed they lie substantially on top of each other for closure into the cassette case. The treads are pushed out of carrier by a gas strut (10, fig 1). The treads are moved from the closed position to the deployed position by the action of a foot pedal 11 with an over-centre spring 12 that also incorporates a position to lock the step against a catch arm 18 in the deployed position.

Description

Step treads closed and carrier frame ready to be pushed closed

Two Tread Cassette Step Unit

Introduction

Many vans and mini buses are fitted with access steps to reduce the step height into the vehicle. For most applications a single tread mounted half way between the ground and the vehicle floor is sufficient. These steps are often mounted under the vehicle floor as single tread cassette units or single tread frame units. However for some applications where the person entering the vehicle is physically limited to the height of step riser they can cope with, it is necessary to have the floor height from the ground accessed with a two tread step giving three smaller risers instead of the two larger risers offered by a single tread step. A two tread step can be provided by a flip over step working with a stepwell cut into the vehicle bodywork. This is expensive in labour to manufacture and fit and can interfere with vehicle sliding door lower tracks. The invention is a cassette step unit mounted conventionally under the vehicle floor, but when deployed provides two treads, the lower positioned below the height of the cassette case and the upper tread sited above the height of the cassette case.

Description

A two tread cassette step unit contains a carrier frame that consists of a pair of side arms 1 (Fig 2) linked together with a cross strut or frame 2 (Fig 2) with the side arms mounted conventionally on rollers 3 (Fig 2) that run on guide rails or channels 4 (Fig 2) incorporated into the step unit casing 16 (Fig 3)that is suitably attached to the vehicle. The rollers and rails could alternatively be slides and pads. The side arms and cross frame assembly are able to travel from a stowed position to a deployed position where stops on the casing prevent it moving any further. A spring means (in this example a gas spring centrally mounted) 10 (Fig 1) is connected to the lower tread unit 9 (Fig 2) and the rear of the step casing 4. The spring acts to push the treads, links and carrier out of the casing. Also acting between the carrier frame 1 and the case 4 is an over centre latch mechanism (not shown) that holds the carrier in the case against the spring force. The catch is released by the carrier frame being pushed in towards the centre of the vehicle a small distance and released. The overcentre latch could be a pedal or hand latch alternatively.

Pivotally attached to the side arms 1 are an outer 5 (Fig 3) and inner 6 (Fig 3) pair of links that pivot on the side arms at pivots 7 (Fig 3). The links are pivotally connected to a top and lower tread 8 (Fig 3) and 9. The links are so designed that they can pivot from a substantially vertical angle when the step unit is fully deployed to a substantially horizontal position when the step unit is stowed. The top tread pivots forwards and the lower tread pivots rearwards on the vertical links so that when stowed, they lie close together to allow the treads, links and side arms to slide into the step casing for stowage taking up minimal height.

A locking pedal or handle catch 11 (Fig 3) that pivots on the lower tread unit 9 and also contains an over centre spring means 12 (Fig 3) a catch arm 18 (Fig 3) and a lever arm 13 (Fig 2) that contacts the outer link pivot point 7 stud 14 (Fig 3) on the outer vertical link 5, is depressed and the lever arm acting on the pivot point stud 14 on the vertical link 5 raises the outer link 5 and consequently the upper tread 4 sufficiently so that it will remain in the raised position by the action of the force exerted by the gas spring 10 acting on the lower tread 8 being sufficient to hold it in this semi raised position. This allows the operator to then transfer his foot from the pedal and push the top tread back towards the centre of the vehicle to the fully deployed position of the step unit. The vertical link 5 has a stop 15 that contacts the catch arm of the pedal arm and prevents the pedal from being pressed beyond the over centre position of its spring means but allows enough angular movement for the lever contacting the pivot stud to raise the top tread sufficiently. When the top tread has been fully pushed back to the operating position, the pedal catch arm drops back to lock against the stud 14 on the vertical link 5 by the action of the spring means. This locks the tread unit 8 in the raised top tread position. The position of the rear vertical link when the catch is engaged is now hard up against the front of the step case 4 at position 17 (Fig 4) and prevents the carrier, links and treads from sliding back into the casing. The step unit is now locked in the fully deployed position and ready to use.

The step is stowed by first depressing the pedal to raise it away from the stud 14 and because the stop 15 is now beyond the reach of the pedal catch arm as the vertical link is in the fully deployed position, the pedal arm can pivot beyond the over centre position of the spring and is held in the fully depressed position by the spring. This frees the vertical link and it can be pivoted forward by the operator's foot acting on the top tread which will then drop down to lie on top of the lower tread.

The action of the vertical link 5 pivoting forwards brings the stop 4 back in contact with the pedal lever arm 13 which rotates the pedal arm back through the over centre position of the spring and the pedal is reset for the deployment mode.

With the treads lying together and the links substantially in a horizontal position the treads, links and carrier frame can be pushed in towards the centre of the vehicle against the force of the gas spring until the over centre catch in the case engages and holds the carrier frame in the fully stowed position.

Claims (1)

1. A conventionally sprung cassette type action step unit, but where the cassette spring acts between the cassette case and the lower tread of an upper and lower tread pivotally mounted on two pairs of link arms pivotally mounted to the main carrier side arms of the cassette unit so that they can swivel from a position where the treads lie on top of each other to a position where the top tread is raised up and the lower tread drops down to create a two tread stair, contains a locking pedal or handle catch that pivots on an end of the lower tread unit, an over-centre spring means between it and the lower tread unit, a catch arm and a lever arm that contacts the pivot stud on an outer vertical link so that if the pedal arm is depressed, the lever arm acting on the pivot stud on the link raises the outer link and consequently the upper tread sufficiently so that it will remain in the raised position by the action of the force exerted by the cassette spring acting on the lower tread being sufficient to hold it in this semi raised position and the pedal angular motion is limited by contacting a stud mounted on the outer link so as the pedal spring does not over-centre and retains a desire to swing the pedal arm in a direction so that when the top tread is pushed back towards the step case as far as the inner link will rotate, the pedal catch arm will drop down and catch the pivot stud on the link and hold the step locked in the deployed state. The pedal arm is then able to be fully depressed passed the over-centre position of its spring means between it and the lower tread to release the catch arm and allow the top tread to be pivoted forward to rest on top of the lower tread prior to allowing the cassette carrier and treads to close into the case. The action of the link swinging forwards reengages the stud with the lever arm of the pedal and brings it back past the over-centre spring position.