The present invention relates to a wheel lift device which is mobile, comprising a base frame provided with wheels on the underside and a wheel carrier which is movable in the height relative to the base frame.

Such a device is advantageously applied in garages during removal and fitting of wheels from and onto passenger cars or trucks. The vehicle is driven here onto a ramp and brought to a height here so that the wheels can be fitted or removed in unloaded state at a suitable working height. A wheel lift device provides the option here of moving a wheel resting on the wheel carrier in upright position to a suitable height for fitting or, vice versa, for removal. As the average diameter of car wheels increases, a wheel lift device has become almost a necessity, since manual lifting has become too difficult or even practically impossible for the mechanic. It has in addition become common to switch winter tyres and summer tyres every six months, whereby a general need has resulted for a wheel lift device which is simple in operation, allows a high handling speed, is easy to maintain and can be produced at a reasonable cost price.

The object of the invention is to meet the above stated general need.

Tn order to achieve this object a first aspect of the invention relates to a wheel lift device which is mobile, comprising:

a base frame provided with wheels on the underside, and

a wheel carrier which is movable in the height relative to the base frame;

wherein the base frame comprises:

a foot part, the underside of which is provided with wheels and the upper side of which is provided with two upright elongate base bars disposed parallel to each other;

wherein the wheel carrier compri es:

a carrier frame comprising two upright, parallel carrier bars and a transverse carrier bar which mutually connects the lower ends of the carrier bars;

a carrier device for a wheel which is provided on a front side of the carrier frame;

wherein the carrier bars on the one hand and the base bars on the other are provided with mutually co-acting guide profiles protruding one into the other and extending over a length of carrier bar and base bar such that the wheel carrier is disposed for movement in the height relative to the base frame, wherein the wheel carrier is movable between a lowest position and a final height,

and wherein the base frame is provided with one or more gas springs, wherein the gas spring comprises a movable operating arm which is connected to the carrier frame and wherein the direction of movement of the operating arm is substantially vertical when the wheel lift device is placed on a horizontal floor.

Such a wheel lift device has a simple and at the same time robust design of the base frame and the wheel carrier, so that usual car wheels can be lifted in stable manner. Through the use of gas springs the lift device comprises an intrinsic power source which is not dependent on external means such as an electric motor for which electricity is required, or a hydraulic lifting system for which a pump is required. The use of the device is thus relatively simple and the costs of the device are relatively low. By providing the base bars and carrier bars parallel and at some distance from each other in the design, the device allows a workspace between these bars within which the mechanic can easily reach the centre of a car wheel for fitting thereof. The carrier device for a wheel is embodied such that a wheel can be placed thereon in upright position and can rest thereon in stable manner. In the wheel lift device according to the invention both base bars are preferably provided with at least one gas spring. The power source for lifting of the wheel carrier i thus distributed uniformly over the construction.

According to a preferred embodiment of the wheel lift device according to the invention, the movable operating arm of the gas spring is connected to a carrier bar. The operating arm of the gas spring is thus connected directly to the object for lifting.

In the wheel lift device according to the invention a first carrier bar is more preferably disposed close to a first base bar and a second carrier bar is disposed close to a second base bar, wherein the guide profile of each carrier bar co-acts with the guide profile of the nearby base bar. This construction produces a very effective lifting force for the wheel carrier. According to a subsequent preferred embodiment of the wheel lift device according to the invention, the guide profiles extend substantially over the whole length of the carrier bar and base bar. Optimal use is thus made on the one hand of the height of the base bar, and a maximum length of guide profile of the carrier bar is utilized on the other, which makes the lift construction robust.

The wheel carrier of the wheel lift device according to the invention is more preferably located at the final height at maximum extension of the gas spring. This final height is reached in unloaded state of the wheel carrier. When two gas springs of 225 N are provided at the two base bars, this height can be reached up to a load of about 25 kg. For heavier loads the mechanic will have to provide some lifting force him/herself.

It is recommended in the wheel lift device according to the invention for the height of the wheel carrier to be adjustable by human effort. The user can thus adjust the height of the wheel carrier as he/she sees fit, for instance by pressing the wheel carrier to some extent downward counter to the force of the gas spring.

In the wheel lift device according to the invention it is further recommended that the height of the wheel carrier is fixable by a clamping means. The manually or

automatically reached height of the wheel carrier can thus be secured, for instance while the lift device is being moved or while a wheel is being fitted.

In the wheel lift device according to the invention the clamping means is preferably provided on the wheel carrier and exerts a clamping force on the base frame. A clamping bolt which presses against the base frame is for instance used for this purpose, or a spring-loaded clamping construction which clamps onto the base frame.

It is also advantageous for the wheel lift device according to the invention to be provided with a latch for locking the wheel carrier in the lowest position. In the lowest position the gas spring is retracted to the maximum and a considerable force is thus required to hold the wheel carrier in this lowest position. This position can be secured in simple manner with a latch, and no more additional force is necessary. The wheel lift device wherein the wheel carrier is in lowest position is moreover a suitable initial configuration of the device: in this position of the wheel carrier wheels can be moved easily from the floor onto the wheel carrier.

In the wheel lift device according to the invention the latch is preferably provided on the transverse carrier bar of the wheel carrier, wherein the latch engages on the foot part for the purpose of locking. Such a position allows simple foot operation of the latch in order to perform a locking or unlocking.

In the wheel lift device according to the invention it is further recommended that in the lowest position of the wheel carrier the carrier device is located close to the surface of a floor on which the wheel lift device stands. It is thus possible to roll a wheel from the floor onto the carrier device without having to lift it manually off the floor.

According to a preferred embodiment of the wheel lift device according to the invention, the carrier device of the wheel carrier is movable in the height to a final height lying in the range between 60 cm and 120 cm above floor height. This is a practical maximum working height for the mechanic, depending on his/her height. The centre of a car wheel placed on the carrier device will effectively lie about 30 cm higher than the height of the carrier device itself.

In the wheel lift device according to the invention it is further recommended that an open intermediate space is present between the carrier bars, the width of which amounts to 30 cm to 50 cm. Taking into account a usual diameter of a wheel rim of between 33 and 45 cm, the open intermediate space provides sufficient space for a mechanic to reach the centre of the wheel rim for fitting purposes.

According to a subsequent preferred embodiment of the wheel lift device according to the invention, the two carrier bars are connected on the upper side by a second transverse carrier bar.

In the wheel lift device according to the invention the two base bars are connected on the upper side if desired by a transverse base bar. The transverse bars on the upper side of base frame and wheel carrier result in a stronger construction. The transverse carrier bar is moreover very useful to the mechanic for exerting a manual force on the wheel carrier during manual adjustment of the height thereof.

In the wheel lift device according to the invention it is recommended that the carrier frame of the wheel carrier is disposed movably between the two upright base bars and that the plane in which the two carrier bars lie substantially coincides with the plane in which the two base bars lie. This construction allows a highly effective use of the force of the gas springs, while the construction as a whole takes a compact and robust form.

In the wheel lift device according to the invention the foot part is more preferably constructed from a planar bar assembly lying substantially perpendicularly of the base bars and comprising:

a foot transverse bar which fixedly connects the two lower ends of the base bars, and two wheel bars which are fixedly connected to the two outer ends of the foot transverse bar, wherein at least one and preferably two wheels are connected to each wheel bar. This simple construction is on the one hand robust and on the other compact, while the wheel lift device remains very stable during movement.

In the wheel lift device according to the invention one or more wheels are preferably embodied as swivel wheels. The user can thus manoeuvre the wheel lift device properly, for instance when little floor area is available.

In a particular embodiment of the wheel lift device according to the invention handles are provided on the base bars on a rear side of the base frame. The user can thus handle the wheel lift device in simple manner while hand contact with the guide profiles of the base bars and carrier bars is avoided.

In the wheel lift device according to the invention the carrier device preferably comprises two rods on which a wheel can rest, which rods are arranged at the position of the lower end of the carrier frame and which protrude from the carrier frame in forward direction of the wheel lift device and lie at a distance from each other. Such rods function as wheel carriers on which a wheel of usual dimensions can rest in upright position in stable manner. The distance between the rods is advantageously at least 25 cm, and preferably at least 30 cm.

The carrier device can alternatively be embodied as a curved plate protruding from the carrier frame in forward direction of the wheel lift device.

The above stated two rods more preferably take a substantially cylindrical form and are connected for rotation about their longitudinal axis to the carrier frame. The rods are for instance embodied for rotation by means of ball bearings. It is thus possible to turn a wheel resting upright on the rods to a desired position without much resistance, for instance when positioning the bolt holes for the bolts of the wheel suspension. The wheel lift device is preferably embodied with the following dimensions: wheel carrier: height about 80 cm, width about 53 cm;

length of bars (carrier device) about 33 cm;

base frame: height about 150-180 cm, width about 60 cm;

height of handles base frame about 90 cm

The gas springs have a spring force of 225 to 250 N.

The wheel lift device is suitable for wheel weights up to 50 kg. The invention will be elucidated hereinbelow with reference to the accompanying figures, in which:

Figure 1 is a perspective view of a wheel lift device according to a preferred embodiment of the invention. Figure 1 shows a wheel lift device 1 comprising a base frame 3 provided with wheels 5 on the underside and a wheel earner 7 which is movable in the height relative to base frame 3. Base frame 3 comprises a foot part 9, the underside of which is provided with wheels 5 and the upper side of which is provided with two upright elongate base bars 11 disposed parallel to each other. Foot part 9 consists of a planar bar assembly comprising a foot transverse bar 20 which fixedly connects the two lower ends of base bars 11 and two wheel bars 22 which are connected fixedly to the two outer ends of the foot transverse bar 20. Swivel wheels 5 are provided on the outer ends of the wheel bars. The two base bars 11 are connected on the upper side by a transverse base bar 24.

Wheel carrier 7 comprises a carrier frame comprising two upright parallel carrier bars 14, a transverse carrier bar 16 which mutually connects the lower ends of the carrier bars, and a second transverse carrier bar 18 which connects carrier bars 11 on the upper side. Provided on the front side of the carrier frame is a carrier device in the form of two rods 30 (one is visible, the second is provided symmetrically on the opposite side), on which car wheel 32 rests.

The two base bars 11 are provided with guide profiles 34 in the form of a slot extending along the length of the carrier bar, which slot is present opposite the respective nearby carrier bar 14. The two carrier bars 14 have a complementary guide profile (not shown) which protrudes into slot 34 of the respective nearby base bar 11. Figure 1 shows the wheel carrier at almost maximum height. Provided for this purpose in both base bars 11 is a gas spring (not shown), the operating arm of which is connected to the guide profile of the respective carrier bar protruding into slot 34 of the nearby base bar 11. The gas spring is disposed in longitudinal direction of the base bar and the operating arm extends in the same direction.

Transverse carrier bar 16 of wheel carrier 7 is also provided with a latch 40 which can be hooked behind the foot transverse bar 20 so that the wheel carrier is secured in lowest position. Provided at the top of the right-hand carrier bar 14 is a handle of a clamping construction 42 with which wheel carrier 7 can be clamped at a determined height. Clamping construction 42 clamps for this purpose on an auxiliary rod 44 which is fixedly connected to transverse base bar 24, and which auxiliary rod extends inside carrier bar 11. Handles 46 are arranged on the base bars at a suitable height on the rear side of the wheel lift device. The figure shows that, because of the chosen construction of base frame and wheel carrier, there is sufficient space within the framework of wheel carrier 7 (i.e. within the framework of carrier bars 14 and transverse carrier bars 16, 18) to reach the suspension points of a car wheel (in particular the bolt holes) for fitting and removal.