If an automated lift or ramp is not part of the vehicle, then a taxi driver is expected to help the disabled person in and out of the vehicle. Usually the drivers of these types of taxis are used to assisting the disabled whether they are in a wheelchair or not.
Generally a typical disabled taxi van can carry four handicapped passengers plus one wheel chair. Some can accommodate more than one wheelchair. This type of vehicle is also often used by hospitals for non-emergency patient transfers.
The main thing about taxi companies who have vans that cater to the disabled is that you need to book them in advance. If you do not bother with this you could be waiting hours for the cab. This is because most taxi companies prefer to book the taxi at half an hour intervals. Most cab companies that do bookings of disabled vehicles also need a booking that is 24 hours in advance. Yet another caveat of these types of services is that their schedules are not always guaranteed. This is because health challenges and various delays as a result of disabilities often cause this type of taxi to be late to their next pickup.